The OMS SmartStream System offers you a choice for single tank or double tank options for diving in total control and comfort. Choose the SmartStream Signature single tank option an it will include weight pockets, a backpad with a storage pocket, and 2 cam bands. The canister/knife holder and left hip D-Ring are added as uninstalled options allowing to switch from single to double tank configuration. Choose the Smart Stream double tank option and it will include, backpad Storage pad, the canister / knife holder and the left hip D-Ring Choose between steel or aluminum back plates and matching hardware (D rings and belt buckle). Finally choose your wing option from our Performance Single or Double wings.