Ultimate Direction Diablo Hydration Backpack (2) 20oz/.6L Bottles Included Weight 17oz/496g Storage 320 in3/4.9L Lightweight mesh material on holster 300D Polyester Baby Ripstop Nylon Mesh Snug fitting, twin V canted bottle holsters prevent bottles from popping out Bottle lock bungee system keeps bottle in place, especially handy during transport Strap Secure webbing control Reflective piping Overflow bungee