The in-board tank is a 13ci (3000 psi) compressed air tank with standard nipple fill and pressure gauge. Shot volume will depend on a number of factors but expect around 200 shots or so. The standard nipple fill allows you to fill the tank in the same manner as other nitrogen/compressed air tanks. The stock body is a standard collapsible carbine model that adjusts in length. There is a slit in the bottom rear for sling attachment. Tiberius Arms includes instructions for an easy installation.