The actuator should be attached permanently to the test apparatus or pressure gauge. The standard actuator is GTP-235-2. A short version, GTP-235-2AH, is available to fit the “S” and “AH” couplers. Both actuators have 1/4” NPT threads. Insert the actuator nipple, and rotate a quarter turn to lock on the bayonet pin. The internal valve automatically opens and a test can be performed.