Is this thermarest first shot at a sleeping bag? I've never seen one by them before
I believe it's their first shot at a fully enclosed sleeping bag. They've been doing a sleep system for 4-5 years that included using their pad with a sheet and a quilt over that. I've handled their bags, they appear nice, light weight, stuff well. I haven't slept in them though so can't say how true the ratings are for temp.