Subscribe Contribute Advertise Facebook Twitter Instagram Forums Newsletter

Therm-a-Rest ProLite Air Mat Product Review

Cascade Designs upgraded their ProLite self-inflating mat once again, with another weight reduction. What were the consequences of weight loss on warmth?


Overall Rating: Recommended

The mat is well-made, lighter than most of the equivalent competition, is comfortable, warm enough when not on snow, and seems quite robust. However the bottom surface slides around on silnylon something awful. For the user to fix this with some stripes of silicone sealant is simple, and Cascade Designs should have done so themselves.

About This Rating

M Find other top product reviews »

Print Jump to Reader Comments

by Roger Caffin |

Technical Details

Therm-a-Rest ProLite 3 Air Mat Product Review - 1
Photo courtesy Cascade Designs.

Alan Dixon reviewed the Therm-a-Rest ProLite 3 back in 2004, when he noted that 'Cascade Designs has whacked more than a quarter pound off their lightest sleeping pad.' The weight for the Small or 3/4 length mat had been reduced to 370 g (13 oz) at that stage. Well, they have reduced the weight even further: the Small (3/4) is now down to 310 g (11 oz). This is getting rather light.

In the process the claimed R-value has dropped a bit, from 2.3 down to 2.2, while the thickness has stayed the same at a nominal 25 mm (1 in). The R-value is going to vary a bit depending on what pressure you put into the mat. This is discussed further under 'R-value.' The nominal length and width dimensions have stayed the same at 505 x 1200 mm (20 x 47 in), ignoring the welded edges. Note however that the mat tapers at the bottom end, down to about 380 mm (15 in).

The foam inside is urethane - as usual with any decent air mat, and the fabric is nylon top and bottom. Both top and bottom surfaces are covered in lots of little dots of something (maybe polyurethane again). The web site says 'Rest Comfortably: Bottom grips and textured top surface hold the mattress in place while you sleep.' This apparently refers to the little dots, but see below for further comment on this.

Therm-a-Rest ProLite 3 Air Mat Product Review - 2
Camp below Matte, Via Alpina, Switzerland.

The foam has had star-shaped holes die-cut out of it to reduce the weight. These holes are visible when the mat is inflated, as you can see here. It is interesting to see that Cascade Designs have chosen the more expensive path of only selectively cutting these holes across the mat. That is, rather than taking a long slab of foam and feeding it through some sort of mass-hole-punching system, they have only cut the holes in the middle of the mat. They have left an unpunched edge down each side and across the bottom and a larger unpunched area at the top end where your head goes. You can see the unpunched edges here too. These unpunched areas are meant to provide extra support at the edges and under your head.

Field Testing

As a background to this I should explain that my wife and I have in the past each used a 3/4 length Therm-a-Rest Deluxe LE mat, which has a very nice soft fabric surface and is about 50 mm (2 in) thick. These have been faithful companions for many years and on many ski-touring trips. Sadly, they are no longer made. The only trouble with them was the weight - 750 gm (26 oz). Some of that high weight was due to the coring used: longitudinal holes. That design did however make the mats quite warm in the snow.

Therm-a-Rest ProLite 3 Air Mat Product Review - 3
Camp at the foot of Glacier de Moiry, Chamonix to Zermatt, Switzerland.

We wanted to reduce our pack weights some more and reluctantly accepted that we needed lighter air mats. The weight of the new ProLite mats was good, but would they be warm enough and soft enough? We took the plunge, got the mats, and set off to Switzerland for another two months walking. The verdict was that they were fine.

I had better qualify that verdict. The mats were normally used on alpine snow grass, as shown here. This can be fairly soft in itself, and does provide some insulation from the ground. Mind you, the water in that tarn was cold!

How are they inflated? Like all good foam-filled air mats, you unroll the mat and open the valve. Go away for a few minutes, and they will self-inflate - up to a point. Typically my wife looks after this while I am looking after the tent: when they seem to have reached equilibrium she gives them about three large puffs and does up the valve. I imagine that over time the puffs might put some moisture into the mats, but we haven't noticed any problems. We always store the mats on their sides inside the house with the valves open when not in use, and I think (hope) that they dry out a bit during storage.

Therm-a-Rest ProLite 3 Air Mat Product Review - 4
Evening at Mumbedah Creek, Kanangra-Boyd NP, Australia.

While my wife likes her mat fairly firm, I often let a tiny bit of air out of mine. Doing so lets my hip get closer to the ground, but if I am not sleeping on snow that doesn't worry me. But the slight reduction in pressure does significantly increase my perception of comfort.

We normally tie our two mats together so we don't get a gap in between. This is good for those cold nights when we supplement the warmth of our UL quilts by snuggling up together. (Hiking with your wife has some advantages!) The photo here shows one of the blue tie straps just to the right of my wife - it was a mid-summer warm evening. However, while this works excellently with the parallel-sided Deluxe LE mats, it is a bit more tricky with the tapered ProLite  mats. The end result is that the foot end of the mats are close together but the foot end is narrower. Well, true, but the narrowness is not a real problem, given the significant weight-reduction.

I had better also add that these are only 3/4 length. I cover the rest of our tent floor with some 5 mm EVA-30 foam. That protects the silnylon floor of the tent and provides just a bit of insulation under my feet. The combination is generally enough, even at some altitude in our Alps as shown below - dawn at 2,100 m (6,900 ft), North Rams Head, Kosciusko NP, Australia. Of course, if we have spare dry clothing available I often fold that up and put it under our feet as well.

Therm-a-Rest ProLite 3 Air Mat Product Review - 5
Dawn at North Rams Head, 2,100 m, Kosciusko NP, Australia.

Sliding Around

We met a significant problem in the field with the way the mats slide around on the silnylon floor of our blue tent. My impression is that the PU dots are really good at sliding on the silnylon, and discussion with my contact at Cascade Designs more or less confirmed this.

I spoke with Doug Jacot, our Therm-a-Rest director. He said that the problem is the Sil-nylon groundsheet. Even the NeoAir, which has one of the best non-slip treatments, can slip on a silicone-treated floor. As you mentioned, adding the silicone sealant stripes to the floor of the tent really is the best option, other than to use a tent without a silicone-treated groundsheet.

Well, as expected, but I have to say that suggesting I change my tent was hardly useful! And I had already added silicone stripes to the floor of my tent, but they seemed to have very little effect on the sliding. I do wonder whether the dots are there not to stop sliding but to prevent abrasion of the fabric surface. The dots are small, but they are packed really close together, and they do slide well.

Therm-a-Rest ProLite 3 Air Mat Product Review - 6
ProLite 3 mat with silicone stripes added.

What the company did not suggest was putting the silicone stripes on the underside of the mat. So I tried this with Permatex Flowable Windscreen Sealant 65AR. You can see the stripes in the photo here. I want to emphasise that these stripes of silicone are really thin: I ran a very thin bead along, then smeared it out with my finger carefully. There are no lumps, and the weight gain would be in the order of maybe 2 - 3 grams. Making the stripes any thicker would not improve their grip. After a rather serious trip in Wollemi NP (a long story...) I can confirm that these stripes made a huge difference: the mat did not slide around. It may be that the silicone stripes on the mat did grip against the silicone stripes on the groundsheet: you may need both. With all due respect to Cascade Designs, I have to ask why they can't do the same thing?


We all know that some companies make exaggerated claims for the insulation value of their clothing, sleeping gear, and mats. We mentioned above that the claimed R-value for the ProLite is 2.2, but obviously this should be measured. Using our insulation test system we measured the ProLite mat with the bottom surface cold and the top surface hot - the way you would use the mat in the field.

Therm-a-Rest ProLite 3 Air Mat Product Review - 7
ProLite mat R-value.

Making the measurement takes time, as mats are good insulators and the heat flow is slow to stabilise. There is always a transient at the start which purely an artifact of how insulation testing works, so we have to ignore that. The plot here shows the R-value at several different thicknesses, from fully inflated (and lightly loaded) to under-inflated and heavily loaded.

You should note that this test started with the mat inflated with a few breaths on top of its normal self-inflation, and this does not completely reflect field use. In the field your hips and your shoulders will depress the mat locally, reducing the R-value right under them. Also, you may not blow the mat up fully as that tends to make it rather hard. When the mat is under-inflated just a little bit you get more of it supporting you, which is more comfortable, although this means some bits of you may be a bit cooler than other bits. That's normal.

My assessment is that the claimed R-value of 2.2 is fairly honest, although if you go for 'comfort,' bits of you will see a slightly lower R-value.


Do we like these mats? For non-snow use, we do. We haven't tried them in the snow, and probably won't. Even though they are thinner (at 25 mm or 1 in) they seem to be quite comfortable, and at 310 g (11 oz) they are much lighter. With a quoted R-value of 2.2 and a measured consistent with that, they have less insulation than our Deluxe LEs (about 6.7) which we use in the winter on snow, but they seem fine for three-season use.


Manufacturer Cascade Designs
Web Site
Model ProLite, Small (3/4 length)
Size (measured) Small: 505 x 1200 mm (20 x 47 in)
Thickness 25 mm (1 in) - approx, depending on inflation
R-value Claimed 2.2, measured 2.5
Weight (quoted) 310 g (11 oz) for Small
Weight (measured) 315 g (11.1 oz) for Small
MSRP US$80 for Small
Other sizes Extra Small: 510 x 910 mm (20 x 36 in), 230 g (8 oz), US$60
Regular: 510 x 1830 mm (20 x 72 in), 460 g (16 oz), US$100
Large: 630 x 1960 mm (25 x 77 in), 630 g (22 oz), US$120

What’s Good

  • Light weight
  • Self inflating
  • Comfortable
  • Seem tough enough

What’s Not So Good

  • They slide around on silnylon!

Disclosure: The manufacturer provided this product to the author and/or Backpacking Light at no charge, and it is owned by the author/BPL. The author/Backpacking Light has no obligation to review this product to the manufacturer under the terms of this agreement.


"Therm-a-Rest ProLite Air Mat Product Review," by Roger Caffin. (ISSN 1537-0364)., 2011-02-01 00:00:00-07.


Reader Comments

You must login to post comments.

New Visitors: Create a new account
Remember my login info.

Therm-a-Rest ProLite 3 Air Mat Product Review
Display Avatars
Sort By:
jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
re on 02/04/2011 08:12:42 MST Print View

"it has been my experience that delam occur directly under where is pivot on my right elbow when moving about. i suspect that the elbow imparts considerable shear into the fabric, and this is a contributing factor."

That's interesting

I'll be more careful putting my weight on it with hand or arm when I get on or off

I'll now watch out for delamination and replace it if needed, thanks for bringing this up

Christine Thuermer
(chgeth1) - F
Delamination on 02/04/2011 20:00:01 MST Print View

I have had 5 delaminated Thermarests and the delamination occured in a different place each time. Therefore I don't think that outside pressure (like your elbow) has any influence on the problem.

For me the delamimation problem is a big issue. The problem usually occurs in the middle of nowhere and it can take me quite a while to get to a place with an outdoor shop. And then that outdoor shop must stock Thermarest and be willing to exchange them under warranty. When on a long hike I have other things on my mind than dealing with defective sleeping pads.... Some countries are very easy when it comes to warranty issues like the US or Germany. But in Australia for example you have to send the mat in for inspection and wait for them to send you a new one. On a long hike you cannot just wait for 10 days till Thermarest is so kind as to replace a defective mat. And in countries like Korea you don't have a chance to get a replacement.

I am still using Thermarest because other mats are probably still no better. But I still think that Thermarest quality is rather mediocre especially considering the rather high price and the persistence of a problem that is known for so long.

Again: It would be interesting to hear a statement for the BPL tech people on that subject. What is the cause for the delamination? Is it really funghus growth? What can the user do to prevent or delay the problem?


Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Delamination on 02/05/2011 00:15:30 MST Print View

Hi Christine

Some of our TaR airmats are now many years (15+) old, and so far I haven't seen this problem on any of them.

> it has been my experience that delam occur directly under where is pivot on
> my right elbow when moving about. i suspect that the elbow imparts considerable
> shear into the fabric, and this is a contributing factor.
I would go further than that and say it was the direct cause of the delamination. I know we do avoid this sort of twisting on our mats. What is happening is probably not 'delamination' per se, but ripping of the very light foam core.

I bet TaR know exactly what causes the delamination. That TaR are willing to stand by their product and take the hit without argument speaks a lot for the company. You simply cannot have UL and bullet-proof at the same time. Make your choice and pick the appropriate brand and model.


Edited by rcaffin on 02/05/2011 00:22:19 MST.

Christine Thuermer
(chgeth1) - F
Delamination on 02/05/2011 06:15:19 MST Print View

The delamination problem is not caused by age, but by use!

Also, you would not have this problem in a 15 year old mat simply because delamination only occurs in mats with punched out foam - and this type of mat was not produced 15 years ago....


Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Delamination on 02/05/2011 13:57:01 MST Print View

> you would not have this problem in a 15 year old mat simply because delamination only occurs in mats with punched
> out foam - and this type of mat was not produced 15 years ago....

Um ... our TaR Deluxe LE mats (limited production) which we bought in the mid-90s and still use on snow trips are cored. And our original TaR mats which they replaced were cored too, and are still in use by one daughter and her family.

Is there a difference between 'cored' and 'punched out'? Dunno, but it would seem that others are still using similar old mats quite happily.


Steven McAllister
(brooklynkayak) - MLife

Locale: Atlantic North East
Delamination on 02/08/2011 19:55:43 MST Print View

I suspect they could make Thermarest pads that are much more durable, but then they would be heavier.
They find that middle ground between what is an acceptable weight and acceptable durability.

A more durable/heavier pad wouldn't sell as well as a lighter less durable one.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Delamination on 02/09/2011 00:33:11 MST Print View

Hi Steven

Reckon you have it.


jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Delamination on 03/29/2011 17:40:29 MDT Print View

I've used my Prolite about 160 nights now.

It's started delaminating:

I bought it at REI so I'll exchange it for a new one.

Maybe it's not unreasonable that a lightweight item wears out after 160 nights.

Roleigh Martin
(marti124) - MLife

Locale: Moderator-JohnMuirTrail Yahoo Group
Re: Delamination on 03/29/2011 17:47:46 MDT Print View

This is the first time I've seen this topic of delamination covered. I'm grateful. I had this happen with my Montbell 150 pad, it was out of warranty, I sent it to Montbell and they sent me a new Montbell 150 pad. Great support. REI also does great support. Mine happened after about 100 nights on the trail.

I always wondered if the detergent or cleaning fluid one uses on the pad to clean the pad might contribute to delamination. Any recommendations for how to clean a pad?

ps. I did not know Montbell would return me a new pad, I was expecting a repair quote instead, and in the interim, REI had a 20% sale on their Thermarest new prolite pads and I got one of those. Now I have two pads, ready for instant replacement (as long as not on the trail) of the next delamination event. Hope it takes more than another 100 nights on the trail.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Delamination on 03/29/2011 19:53:06 MDT Print View

When I get onto my pad, I often put my hand where it delaminated and put all my weight on it.

That, and I sit there and swing me feet around to the foot end.

I think if I didn't put all my weight on my hand it probably would last a lot longer.

Peter Jones
(tracksterman) - F
TAR delamination on 04/23/2013 20:48:10 MDT Print View

Nice to see someone (Christine) sticking their head above the parapet.

The old TARS lasted forever because they were more durable (and thus heavier). I also had one (an Expedition 3/4 length model) for over 15 years, before I stupidly 'upgraded' to a lighter Prolite 3. Since then I've been through the P3 and two Prolites; the most recent was bought autumn 2012, so this is NOT an early product run problem; it had at most three months' 'realtime' use on it before it delaminated.

Anybody familiar with the old petrol-tank-in-the-car-boot story?

This is not user error. It's quite simple. Thermarest suck up warranty replacements from people actually using these mats because they make more money out of not addressing the durability problem. Rather, they sell lots and lots of lightweight mats to people who don't use them enough for the problem to occur. My own feeling is that the cutouts are too big; there just isn't enough surface area left to bond to inside the mat. Resolve the problem, the mat gets heavier and thus it doesn't sell.

It's not just Thermarest, they're all at it. I had a POE mat that lasted 2 1/2 weeks before internal seams ripped out in two places. The UL apologists will now say it's my fault. Yeah, yeah, and she was asking for it dressed like that, y'honour.

There is an easy solution. It's called a Multimat Expedition Summit XL CCF mat.