Its a waterproof nylon bivvy... waterproofing on the inside...very lite weight....reasonable quality...I just put it straight over a sleeping bag and then put the sleeping bag straight back into it's stuff sack... It came with it's own stuff sack but I'll use that for something else...as a bivvy it work's fine and adds an extra layer of warmth to the sleeping bag as well...For what it costs it's reasonable value for money so not bad at all !