I got a 20 deg. slick bag this year, & for me the jury is still out. May be some weird California chit, but I took it out for the 1st time w/ temps no lower than about 35 & froze till layered up. I was also in my Tigoat bivy. Possible that going from 70 deg. nights here @ home to 35 deg. nights out there for the first time this year had something to do with it? A couple of weeks later @ higher elevation & lower temps, same bag & bivy & I was fine until the last night when it got down to 25 when I used my spirit quilt from mountain laurel designs inside the slick bag to keep toasty. My 38 deg. spirit seems true to its rating, but I only have 9 or 10 nights in my slick bag. Hopefully I will learn to like this bag.