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Integral Designs eVENT Overbag and Micro Bivy SPOTLITE REVIEW

Utilitarian bivy sacks that perform their core functions well in the absence of excess luxuries and weight.

Hightly Recommended

Overall Rating: Highly Recommended

When rating these two bivies, I had to force myself into realizing that these products are aimed at two types of users: (1) those who camp with other overhead shelters and want a waterproof bivy sack for complementary protection and warmth, and (2) those who use bivy sacks as a standalone shelter and are willing to accept some sacrifices in terms of full weather protection.

Each of these bivies serve the former group (1) well. Specifically, the Overbag/Bivy is a superb bivy sack for use while sleeping on snow, in combination with a snowcave or other floorless shelter. Its greater breathability, lighter weight, and slightly simpler hood easily offset the disadvantage of the less durable floor.

Each of these bivies also serve the latter group (2) well, but two important considerations must be made. The first is that of durability - the Overbag/Bivy's eVENT floor will not withstand repeated use on rocky ground without suffering some abrasion. Personally, I could care less about that. I've worn minor holes in all of my bivy sack floors, and never notice them, even in hard rain. It's just the nature of how bivies get abused. Second, and more important, if you are using one of these bivies as a standalone shelter, the Overbag/Bivy gives you the option to flip the bivy over for additional weather protection in case of hard rain. I found that to be particularly advantageous in a few situations, even in the summer, but only above treeline. Below treeline, with the Micro Bivy, I simply moved my pitch so that the head end of my bivy was protected under the shelter of a tree or bush.

So, in summary, while I give a rating of HIGHLY RECOMMENDED to the eVENT Overbag/Bivy, I have to downgrade the Micro Bivy to RECOMMENDED for the reasons outlined above.

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by Ryan Jordan |

Integral Designs eVENT Overbag and Micro Bivy SPOTLITE REVIEW


Integral Designs has expanded their range of bivy sacks with two simple models built around their eVENT fabric program.

The eVENT Overbag/Bivy is positioned as a "bag cover" designed to complement your existing shelter system (e.g., tarp, tent, or snow cave). The eVENT Micro Bivy, on the other hand, is positioned as a standalone shelter. The purpose of this review will be to discuss their key differences, and the performance of both in the field.

Both bivies are light in weight, and indeed, are the lightest weight eVENT bivy sacks on the market. The 88" long (girth measurements are 72" at the chest, 64" at the hip, and 58" at the foot) eVENT Overbag/Bivy weighs (on our scales) only 17.7 oz. The eVENT Micro Bivy (also 88" in length, with girth measurements of 72/64/52), which uses only marginally less fabric by reducing foot girth, weighs slightly more - 19.1 ounces.

The differences in weight are related predominantly to differences in fabrics used for the floor. The Overbag/Bivy uses 3L (3-layer) eVENT ripstop for both the upper and the floor, and the Micro Bivy uses eVENT only for the upper, opting for a more durable 70 denier coated (waterproof nonbreathable) nylon for the floor. As noted above, the Micro Bivy has a slightly smaller foot girth (six inches), which doesn't impact weight a great deal, and is not noticeable in use unless the foot of your sleeping bag has a very large girth.

The final difference between the two is in their hoods, which use the same patterns, but offer slightly different closure systems. The Overbag/Bivy offers a non-stretch drawstring only for the lower half of the hood opening, which allows you to seal the chest of the bivy against drafts. The Micro Bivy offers a stretch drawcord over the entire perimeter of the hood opening, for more weather protection. I found the non-stretch drawcord to slide more effectively through the drawcord tunnel, and preferred it to the stretch drawcord. However, I preferred the ability to have both drawcords available for maximum weather protection.

Field Performance

I used both bivy sacks in rain and snow as standalone shelters, under tarps, and in snowcaves.

I preferred the Overbag/Bivy over the Micro Bivy in every situation. It's lighter, the hood drawcord slides easier, and the use of eVENT throughout the bivy offered the best breathability. I found that condensation accumulated on the sidewalls of the 70d nylon floor of the Micro Bivy in very cold and wet conditions. In similar conditions, much less condensation formed on the inside of the Overbag/Bivy.

The eVENT floor of the Overbag/Bivy allowed me to flip the bivy over when using it as a standalone shelter in driving snow and rain. This allowed me keep the hood opening facing downward and protected from moisture entry. I was not able to do this with the Micro Bivy, because its coated floor would have resulted in prodigious accumulation of moisture in the bivy resulting from condensation.

This asset of the Overbag/Bivy is also a disadvantage: its eVENT floor is less durable than 70d nylon, and I found that after several outings where I pitched the bivy directly on rocky soils (visualize the typical alpine mountaineer's bivy), some wear resulting from abrasion was apparent. I observed no abrasion on the Micro Bivy's nylon floor with similar use.


  Overbag/Bivy Micro Bivy
Weight 17.7 oz 19.1 oz
Floor 3L eVENT ripstop 70d coated nylon taffeta
Upper 3L eVENT ripstop 3L eVENT ripstop
Hood Closure half-drawstring, non-stretch full-drawstring, stretch
MSRP $210 $185

What's Good

  • eVENT fabrics effectively resist condensation better than Gore-Tex fabrics
  • Simple designs minimize weight while affording some weather protection
  • eVENT floor on Overbag/Bivy allows it to be flipped to offer additional protection from water entry into the hood

What's Not So Good

  • Hood drawstrings on both bivies are difficult to use
  • Hoods are ineffective at keeping moisture out in inclement weather


"Integral Designs eVENT Overbag and Micro Bivy SPOTLITE REVIEW," by Ryan Jordan. (ISSN 1537-0364)., 2006-08-01 03:00:00-06.


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Integral Designs eVENT Unishelter SPOTLITE REVIEW
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Ryan Jordan
(ryan) - BPL Staff - MLife

Locale: Greater Yellowstone
Integral Designs eVENT Unishelter SPOTLITE REVIEW on 08/01/2006 23:02:27 MDT Print View

Companion forum thread to:

Integral Designs eVENT Unishelter SPOTLITE REVIEW

Ryan Jordan
(ryan) - BPL Staff - MLife

Locale: Greater Yellowstone
Overall Ratings By Reviewers on 08/01/2006 23:03:24 MDT Print View

I'm particularly interested in hearing from the readership whether the "overall rating" section offers any useful value to the reader, as we are considering adding this to all reviews as a standard section, and then providing the website visitor the ability to query all product reviews by this and other fields.

Edited by ryan on 08/01/2006 23:04:25 MDT.

kevin davidson
(kdesign) - F

Locale: Mythical State of Jefferson
overall ratings on 08/02/2006 01:10:29 MDT Print View

A similar system is used by the Digital Photographry Review website to good effect. Although all rating systems are fraught with their own particular quirks and limitations, this one seems resonable for a broad relativistic treatment of a product. It's a hook for the reader to peruse the in-depth write-up of the goods.

Jeroen Wesselman
(jeroenman) - F

Locale: Europe
overall rating on 08/02/2006 01:13:49 MDT Print View

I must say I like the overall rating but I think that the overall readership of BPL is educated enough to make up it's own opinion about the reviewed products. In case of BPL, over the years BPL and the reviewers really earned my trust, that's what makes these overall ratings much more valuable for me. I'am much more reserved with review ratings from other magazines or so called backpacking sites.
I would say go for it!

Glenn Roberts
(garkjr) - F

Locale: Southwestern Ohio
I like the rating system on 08/02/2006 05:34:05 MDT Print View

I like this descriptive rating system better than a 1-5 scale. Usually, the 1-5 ends up being an attempt to give the impression that the rating is far more scientific and objective than it really is.

The descriptive scale, and the deliberately "soft" definitions each description is based on, are perfect for my needs. "3" tells me only that, for some reason, someone liked it better than the "2" item, but less than the "4" item. "Above average" is useful to me as a consumer: this isn't junk, and I should look at it - but I should also look at some other similar items. "Highly recommended" tells me I really don't need to look any further (if my needs are pretty similar to the reviewer's.)

The numerical scale is OK for our reader reviews - they provide a mechanism to average out the input from a number of people - but for the single-reviewer article, I really like the descriptive overall rating.

Channing Sze
(eeyore) - F
possibly misleading on 08/02/2006 09:14:05 MDT Print View

a numeric rating is usually ok, BUT only if there's lots of reviews (>10?). an average based on a few reviews is too easily skewed. for example, waits for a few reviews before releasing their results.

Chris Jackson
(chris_jackson) - F
could be lighter on 08/02/2006 20:31:25 MDT Print View

I have a Sierra Designs Divine Lightning (DL) Bivy Tent, a relic from the 1990's.

Upper looks fairly similar to Bibler's Toddtex, though the material is not specified on the label. Floor is heavy PU-coated nylon.

Unlike the Unishelter, the DL is tall enough to sit up in; a major advantage IMHO.

The DL without poles or pegs weighs just 32 oz!

Although the DL was designed to use Easton poles at the head and foot of the tent, it could be modified to use trekking poles at the head together with the short Easton pole at the foot. So for roughly 32 oz plus trekking poles you get a fully functional one man goretex tent.

Why is it that, nearly ten years after the DL was produced, a less functional Unishelter design weighs almost as much as the DL?

Ryan Jordan
(ryan) - BPL Staff - MLife

Locale: Greater Yellowstone
Re: could be lighter on 08/02/2006 20:41:18 MDT Print View

Chris, you're right. The DL tent was a great design. I have one and used it to the point of no return. The floor needs replaced badly.

Its limitations relative to the Unishelter include poor breathability and a longer footprint. The latter isn't a big deal but I've spent some pretty uncomfortable wet nights in the DL, especially in the winter, where in similar conditions, the eVENT Unishelter performed well.

Sebastian Ventris
(sabme) - F - M

Locale: SW UK
lighter on 08/05/2006 14:36:00 MDT Print View


More importantly to me than the rating system would be a simple summary and conclusion when I don't have time to read pages of technical literature. I find some of the reviews on BPL excessively scientific and long winded. Not to say I don't appreciate your efforts.

Why so much excitement about these products? I've been sleeping in much lighter bivy bags with no tarps and getting rained on directly for years. My old Rab waterproof breathable Pertex bag is lighter and my current MontBell Breeze Dry-Tec is much lighter.

I always use a synthetic sleeping bag and sometimes have to improvise a vapour barrier liner from some plastic bags to avoid excessive condensation in prolonged bad weather. But mostly camping under trees is enough.


Johan Engberg

Locale: Wrong place at the right rime
Update on 04/13/2007 07:49:51 MDT Print View

I recently bought the Overbag and it has now the same stretch drawstring system in both hood and body found in the micro bivy.

James Crockett
(davidcrockett1958) - F
Re: lighter on 08/07/2007 00:52:06 MDT Print View

"More importantly to me than the rating system would be a simple summary and conclusion when I don't have time to read pages of technical literature."

I like both. A rating and a summary. The digital camera site mentioned earlier is great and they provide a conclusion like summary and a rating like "highly recommended" or "recommended". In the summary they also give you the reason(s) that said camera (insert any product)was given recommended and not highly recommended.

Overall, I think this is a great idea!

Dave -
(FamilyGuy) - F

Locale: Up there
Revised Unishelter on 08/13/2007 22:04:07 MDT Print View


Edited by FamilyGuy on 11/01/2013 09:59:11 MDT.

Donald Browning
(docdb) - M

Locale: SE USA
Agree, David on 08/17/2007 21:38:44 MDT Print View

The unishelter is my favorite!