I got an REI bag, about 20 yrs ago. I think its a Volcano, synthetic but I'm not sure what kind. It seems to live for ever. Lives in a stuff sack, gets washed, keeps me warm on the ground, in a tent, in a hammock. I want to convert it to a top quilt, but we've been together so long I'm having a very hard time taking scissors to it. My down filled gortex covered Feathered Friend was smaller and lighter, but it didn't last very long.