This is a drysuit undergarment from "OS Systems" drysuits. The size label has worn out of it so I am estimating that is a medium. It is sort of like polar fleece or an imitation lambs wool textured fleece lined undergarment. I don't know the exact weight but I'd guess it to be equivalent to a 200g undergarment. It's not super sexy but if you're on a budget, it will get the job done.
