Field service coupler 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 High side and low side are sold separately, one coupler per order. Allow access to service ports on automotive R-134A A/C systems.