Waterproof and breathable in order to avoid condensation inside the bag, the TRILOGY BIVY ultra-light mountaineering overbag is designed to combine with the TRILOGY QUILT sleeping bag to compose a kit weighing less than a kilo, made for high altitude bivouac. Field-tested by our technical experts, mountain guides and mountaineers, it is made of very light and breathable PERTEX® SHIELD XLIGHT 3L, assembled with waterproof seams to provide efficient protection against the rain and snow, without generating moisture inside. Compact and functional, this MILLET overbag has a hood with a draw cord and comes with a compression bag.