Sea to Summit Air Chair Durable 70D base with 2000mm waterhead protects your mat from rough or wet ground. Back panel and strap anchors sewn from high tenacity, abrasion resistant Ultra-Sil fabric. Lightweight design through minimalist panels, straps, and buckles. Elasticized gusset keeps mattress protected from the side. Regular Air Chair fits small and regular Sea to Summit mats and the Large Air Chair fits large Sea to Summit mats.