I recently found a "used" but mint condition military surplus four-part sleep system. It comes with the green "patrol" bag, the black "intermediate" bag, and the woodland camo Gore-Tex bivvy bag, with a black stuff sack for the lot. I've seen them for anywhere up to $200, so I was pretty happy to get it for $75 delivered.

I've read that if you store synthetic sleeping bags compressed for long periods that the insulation will lose its value. First, is this true? Second, what constitutes "long periods"? I bought this bag primarily to keep in my car during winter months.