The set includes high and low pressure adapters. The central core of the connectors is adjustable to fit different valves. They are connected to the valves of R134a air conditioning systems and provide an opportunity to service these systems. These quick connectors are designed to prevent various injuries and loss of refrigerant if the connectors are disconnected at high system pressure. The compact design of the adapters allows you to reach even hard-to-reach places and service a large number of cars equipped with an R134a air conditioning system. The 6-ball system allows for extremely accurate centering of the adapters when they are installed. They are connected using 1/4" SAE threads.