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. <br /><br />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.