The Zpacks 10f Mummy Sleeping Bag is a full mummy-cut bag with an integrated hood, filled with 531 g of 900 fill-power duck down treated to be hydrophobic, meaning it resists moisture better than untreated down. A -12°C (10°F) temperature rating combined with a 745 g total weight makes this a bag for genuine winter conditions, where full-body coverage matters more than shaving every last gram.
A full-length two-way zipper allows the bag to be opened from top and bottom simultaneously, useful for venting the feet on milder nights, while a fitted, adjustable hood, draft collar and draft tube all help trap warm air — details the hoodless Classic version skips. The 7D Ventum Ripstop Nylon shell with DWR treatment keeps the bag lighter than a comparable ordinary nylon fabric.
Compared to the hoodless 10f Classic, it weighs over 150 g more, but delivers more complete thermal protection without needing a separate head-insulation solution, which suits hikers who value simplicity over squeezing out every gram.