Sea to Summit SN240 Ultra-Light Siliconized Cordura Pack Cover nylon 30 D Diamond Ripstop Sil Cordura Weighs 2 oz (X-Small); 3 oz (Small); 4 oz (Medium); 4.6 oz (Large) No seam construction for complete waterproofness Mid back keeper strap Packaged in its own mini silconized nylon stuff sack