Low-Side Manual Coupler, Blue Actuator Field service couplers connect to our special Enviro-Guard hoses to allow access to service ports on automotive R-134a A/C systems . The quick-connect design has an integral safety sleeve, which protects against injury and refrigerant loss if the coupler is disconnected under pressure . The compact design easily fits into tight quarters, which is especially handy for retrofits . Six-ball couplers provide a more stable grip on the fitting than do couplers with four balls 18190A No -