The Gas Switch Block by OmniSwivel International offers a diver the ability to change between two separate gas supplies without having to remove a full face mask. To make the switch, the knob turns a full 180-degrees, ensuring that there is no accidental switching during the dive. When the knob is centered it is in the shut-off position. In case of a second stage failure, a diver can turn the flow to the mask off and switch to an alternate regulator. The shut-off position also prevents a cross blending of gases during a switch over.

The V2 version Gas Switch Block can be converted from right to left. It has two 9/16-inch male inlets and one 3/8-inch female outlet. The block is constructed of solid brass for maximum durability, and uses oxygen compatible materials and o-rings. The 9/16-male inlet adapters can be removed to expose 1/2-inch female ports, allowing for hose attachment flexibility. Quick disconnects can be attached directly to the inlet ports, alleviating the need for more adapters.