Ogio Erzberg 70 Hydration System - 70 Ounce/Black 600D/400D Polyester exterior construction has a DWR coating to defend against intense climate condit Low profile design and style fits under or over the roost deflector and the jersey Two stretch mesh One piece zipper pulls alleviate weight as well as noise during active quests Padded Air mesh back panel designed for wicking away moisture from your body for more comfort Ergonomic mesh shoulder strap along with modifiable sternum strap and tube routing system