The UltraLamina’s warmth rating seems dead-on, with all of our testers agreeing they were warm – almost too warm – during 40º nights and they were comfortable as the conditions approached freezing. Add to that the bags remarkable compactness and light weight, and the UltraLamina comes close to being the perfect fast-and-light summer backpacking bag. A little extra legroom would have clinched that status.

Compressibility
When it comes to packing your bag, you won’t get much smaller than the fully compressed UltraLamina. Using the included compression stuff sack, the UltraLamina shrinks to a mere 7-inch ball – the smallest we found in synthetic bags.

Warmth to Weigh
Coming in just under two pounds, the UltraLamina matches most down bags in this temperature range for weight. Mountain Hardwear’s proprietary Thermal.Q insulation compresses well, but lofts up quickly once pulled out of the stuff sack, resulting in a great warmth-to-weight ratio.

Comfort
The UltraLamina’s hood fits perfectly, and most testers felt the upper section of the main body of the bag was comfortable, though I – as the ‘bulkiest’ tester (48-inch chest, 36-inch waist) – felt the entire bag was slightly constrictive. Everyone agreed, though, that a couple extra inches in girth around the lower legs and feet would have been ideal. I also missed the ability to let some air in around my feet during warmer nights – the ¾-length zipper limits venting options. For more moderately sized campers, the bag was rated good to okay on comfort throughout.

Durability
The thin 15-denier shell keeps down the weight and bulk, but leaves the bag susceptible to snags and tears. We found that a fold of the slick, thin shell would occasionally catch in the small-toothed zipper, creating a tiny run or tear in the rip-stop nylon. Long term, this could be problematic. But the loft of the synthetic fill never diminished and the general durability seemed good.

EN comfort limit = 40ºF / 4ºC
EN Lower Limit = 32ºF / 0ºC