I’ve used the Lark UL 10 for the past several years during the winter months when I’m expecting temperatures to be between 0 deg F and about 20 deg F. I pair it with a down parka, pants, and booties for the low end of that range.
The coldest nights I’ve spent with the Lark 10 have been in bivy sacks in exposed winds, and temperatures in the single digits or lower. As to be expected, I supposed.
Things I like:
- water-resistant shell
- wide enough girth to layer puffy clothes but narrow enough to be efficient – good balance
- terrific cinch system for the hood and collar – no-stretch hood cord, stretchy collar cord.
- one of the lightest bags for its loft on the market – my size R is 31.2 oz
Things I would like to make this bag perfect:
- a half-zip, down the center – I spent a lot of time in my bag in the winter sitting up cooking, etc, and a half-zip down the center would make it easier
- a wider girth (slightly) – I could see this bag being extended to even colder temperatures with a winter-class parka like the Grade VII – but that would be too tight in the bag as is right now
Image: it’s my go-to bag for all of my 1-2 night winter bivy trips the past few years.