The Vindicator Visual Safety Tank Valve Air On/Off Color Indicator For Scuba Diving Cylinder The Vindicator Visual Safety Tank Valve Air On/Off Color Indicator The Vindicator handle and colored rings replace the original valve handle When valve is turned off, red ring is 100% visible, When valve is turned on, the green ring advances over red ring The Vindicator was designed to be an easy to read visual safety device to prevent divers from starting a dive with their air turned partially on or turned off completely