Crux B1 Scout Bivvy Bag

A glorified sleeping bag cover, the B1 Scout is as simple as a bivi bag gets. It has a drawcord around the face, but you can never completely seal the face area and there is no mesh insect screen. The design may be plain, but the B1 Scout's X-tex fabric is decidedly hi-tech. X-tex fabric has a woven textile face with a coating to make it both waterproof and breathable, with a 50 denier polyester face. 50 denier is a heavy yarn by today's standards, but Crux consider it important for a mountaineering tent, since the intrinsic strength of fabric is derived primarily from the thickness of the yarn. Unusually Crux has chosen polyester rather than nylon, as polyester offers superior resistance to UV degradation.