This special coupler allows you to connect to a Schrader valve and open the valve in two separate operations. This is particularly important for high pressure applications (such as pressurizing racing shocks) to prevent pressure from leaking out when connecting and disconnecting. The same fitting is used on the Penske Shock Inflation Tool (Part No. 8021-001).
If your fuel-injected car has a Schrader valve on the fuel supply line, this fitting can be used for taking fuel samples at Impound or for checking fuel pressure without spilling fuel. The 1/8 NPT male fitting can easily be adapted to a 4AN or 1/4" rubber hose to direct the fuel sample away from the hot engine.