The trailhead is not hysterically thin - the fabric has been chosen for a nice and longservice life. The surface fabric is 40 denier ripstop nylon with a polyurethane coating, material weight 108g / m². Use as is at the base of a spruce tree, or in conjunction with a tarp. A bivy sack is a rugged way to avoid using a tentoriginally developed for emergency situations, this protective cover for your sleeping bag prevents wind from replacing the warm air trapped inside your bag with cold air, and the material also keeps light rain from getting in. On the downside, a sleeping bag and bivy combo doesn't breathe as well as a sleeping bag on its own. - Waterproof, breathable - Taped seams - Zipper-free structure: entry and exit via snap-closure mouth - Length 250 cm - Width at the shoulders 85 cm - Pack size 18 x 12 cm The fabric is impregnated to be water repellent without the use of PFCs. Note! This product is a protective bag to be used on top of your sleeping bag. It does not provide