FEATURES of the Klymit KSB 20 Three Season Down Hybrid Mummy Sleeping Bag, 82x30in. 650 fill power down top and synthetic fill bottom provides exceptional warmth-to-weight ratio. Anti-snag, two-way YKK zipper opens from the bottom or top to easily control the flow of air. Built-out foot box for plenty of comfort where it’s needed most. Mummy hood with draft collar and draw cord reduces draft. Packs down small with included compression sack. Insulation Type: 650 Duck Down (Top)/Synthetic (Bot).