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Mountain Laurel Designs Devotion 40 Sleeping Bag SPOTLITE REVIEW

Is an 11-ounce, 40-degree bag possible? Nunatak thinks so, and now so does Mountain Laurel Designs.


by Carol Crooker | 2006-03-22 03:00:00-07

Mountain Laurel Designs Devotion 40 Sleeping Bag SPOTLITE REVIEW


The Mountain Laurel Designs Devotion 40 is an 11-ounce hoodless top bag with a generous 3.1 inches of loft on top and an enclosed, fabric bottom. The bag is wearable, with a bungee-closed bottom and snap at the collar so the side zipper can be partially undone to form an armhole. The tested bag also has a short armhole zipper opposite the side zipper (optional) so both arms can be outside the bag.

Ron Bell of Mountain Laurel Designs has designed the Devotion series of bags for sub-5-pound three-season and sub-10-pound winter pack weights. The Devotion 40 cuts weight with very lightweight fabric and notions, high quality down (900 fp), and a slim width. The size Regular Devotion 40 is too narrow for Backpacking Light Publisher, Ryan Jordan (shoulder girth 49-50 inches), and just wide enough for me (shoulder girth 44 inches). The Regular length is long enough for my 5'10" frame.

I've had a prototype of the Devotion 40 for a few nights sleeping thus far. My preliminary findings follow.

The fabric bottom of the Devotion 40 is narrower than the insulated top. The Devotion 40 is warmest when I sleep on my back and the insulated top just drapes to the sleeping pad on both sides. Sleeping on my side, there is a gap in insulation at my back that lets in drafts even after I shift the bag for best coverage - that's both with, and without, a pad bungeed to the bottom of the bag. The down portion of the bag is just wide enough to cover the top and two sides of my body when I'm on my back. When I shift to my side, the bag insulation must now cover my front, back and one side - but it's not wide enough to do that. The Devotion 40 circumference is large enough for me and even allows me to wear an insulated top inside without loft degradation. In fact, the Devotion 40 is very similar in width measurements to the Western Mountaineering HighLite, a favorite of mine. The Devotion 40 would be warmer for side sleepers if the insulated top accounted for a greater percentage of the bag's circumference. But keep in mind I'm talking about an 11-ounce bag here!

Mountain Laurel Designs specifies that their temperature rating is dependent upon practicing good lightweight techniques including using a bivy sack and wearing all your clothing. Thus far in my testing, I've found a hooded down vest (another Mountain Laurel Designs prototype) to be a perfect complement to the Devotion 40. Backpacking Light co-founder, Alan Dixon, has long recommended wearing an insulated top to get the most out of a top bag and that advice is true for the Devotion 40. The hood of the vest acts as an articulated sleeping bag hood since it shifts with you as you roll and, more importantly for me as a dedicated side sleeper, the vest's torso insulation keeps the chill off my back when I'm on my side.

Wearable - It's a nice option to be able to sit up or even stand up while wearing the bag yet still have your hands free. The footbox of the size Regular Devotion 40 is just wide enough to slide up over my 44-inch hips, making for cozy bathroom breaks. There is no insulation on the back of the bag, but sitting leaning against a tree with foam pad behind you might be adequate (although there will still be no down on the tops of your shoulders - a spot that gets cool on me). I tried out the Devotion 40 briefly in a hammock and it shows real promise. After donning the bag like a garment, it was easy to get into a bottom entry Hennessy hammock and then cinch the bottom of the Devotion 40 closed. I didn't feel any drafts during a short nap, and am eager to try the Devotion 40 out overnight in a hammock.

The Devotion 40 is designed for extremely weight conscious backpackers. It has lots of loft for the weight and a lot of thoughtful details such as a snap at the top of the zipper, tethered cordlocks and bungee closures at foot and neck, zipper tabs with attached pulls on the inside and outside of each zipper, and loops and supplied bungee for attaching a sleeping pad. There is only one other commercially available sleeping bag/quilt this light, the Nunatak Arc Edge (see our review of its big brother, Arc Ghost here). Tom of Nunatak and Ron of Mountain Laurel Designs take markedly different approaches to 11 ounce, 40 °F top bags.

Features and Specifications

  • Style: Hoodless top bag
  • Backpacking Light measured weight: 11.1 oz (315 g)
  • Down: 5 oz (142 g) of 900 fp size R
  • Baffles: sewn through, continuous across top of bag, spaced 8 in (20 cm) apart
  • Backpacking Light measured loft: 3.1 in (7.9 cm) average at baffle center
  • Manufacturer temperature rating: 40 °F (4 °C) when used with a bivy sack and wearing all your clothing
  • Shell fabric: Momentum 90 DWR, 20d x 20d symmetrical tight weave nylon taffeta, 0.9 oz/yd2 (30 g/m2), interior is heat calendared for downproofness (the test sample has different shell fabric)
  • Bungee sheaths: Epic by Nextec, 1.7 oz/yd2 (58 g/m2)
  • Thread: Decot Tex 30 and 40 water resistant hydrophobic poly wrapped poly thread for strength and micro size needle to prevent down leakage at seams
  • Notions: 45 in (114 cm) #3 YKK water resistant zipper; Bungee 0.65 g/ft; Mini Cordlocks 0.03 oz (0.7g) each
  • Sizes:
    SizeWeight oz (g)Shoulder Girth in (cm)Foot Girth in (cm)Fits Height ft-in (cm) Fits Weight lb (kg)
    Small10.5 (298)54 (137)40 (102)5'6" (168) 145 (66)
    Regular11.1 (315)58 (147)42 (107)5'11" (180) 180 (82)
    Large11.9 (337)62 (157)45 (114)6'3" (191)210 (95)
    X Large12.5 (354)66 (168)48 (122)6'6" (198) 240 (109)
  • Included: Spinntex Pro (0.97 oz/yd2, 33 g/m2) stuff sack, average weight 0.35 oz (10 g), mesh storage sack, bungee and two cordlocks to secure pad to bottom of bag
  • Features: bungee drawstring foot and neck, snap closure at neck, insulated top is 60% of the total girth for wrap around side insulation, loops along the bottom seam to be used to secure a pad to the bag or tighten girth, 45 in (114 cm) water resistant side zipper
  • Options: Devotion 40 PRO with no zippers or foot opening, 10.25 oz (291 g), $155; 16 in (41 cm) armhole zipper on side opposite standard zipper; Epic fabric (adds 20% weight and 10% price); 20% overfill $40
  • MSRP: $175 S and R, $185 L, $195 XL


"Mountain Laurel Designs Devotion 40 Sleeping Bag SPOTLITE REVIEW," by Carol Crooker. (ISSN 1537-0364)., 2006-03-22 03:00:00-07.