Kayu men’s and women’s ultralight down mummy bags are pinnacle equipment for ultralight adventures. Careful tailoring of the hood, footbox, and body-mapped core creates an optimal fit with no excess weight or wasted space. Premium 800 FP down and aggressive, thermally efficient patterning make for a trusted companion on longer journeys where every ounce matters. Our flagship Thermo Gills allow you to regulate temperature without letting in drafts, deeply extending the useable temperature range. The waterproof/breathable footbox and hood protect from tent wall condensation. Our exceptionally packable 800 FP down is hydrophobic, PFC-free, and 100% Responsible Down Standard (RDS) certified. Top-shelf fabrics include a 20D nylon ripstop with DWR on the shell, an ultra-smooth 30D nylon taffeta lining, and a 40D nylon ripstop waterproof/breathable footbox.