Quick-change connectors, one is with a one-way valve, one is without a check valve. Application with check valve,Hydraulic hose check valve and the gas source is connected to the end, when you disconnect the check valve closes automatically when you turn on the activity side thimble-way valve is opened. Is the use of self-locking ball is embedded in the groove, while the locking balls from "tapered cylindrical ---" sleeves.