Fluorocarbon O-Rings stand up to aggressive detergents and up to 300° F. These o-rings fit most quick connect couplers and sockets. Most of the time, if your fitting is leaking, you can easily replace the o-ring with just a dental pick. The 1/4" rings fit the socket that goes on your wand and holds QC nozzles in place. The 3/8" o-rings fit the couplers and sockets that connect your hose to your gun to your pressure washer.