This size expander adds up to 6.75 in / 17 cm of extra chest room in the Super Down Altai Sleeping bags, making it ideal for side sleepers and larger individuals. Built from the same materials as the Altai Sleeping bag, including a combination of Quixdown and 3DeFX synthetic insulations, it maintains the effective warmth of your bag while adding shoulder room. This expander will retrofit on the regular length Super Down Sleeping Bags predating 2024. It will zip into the long size; however, the expander does not extend the full length of the bag’s extended zipper.