Pressure washer screw couplings are used anywhere high-pressure connections are frequently assembled and disassembled. They connect to all common 1/4 in (6.35 mm) or 3/8 in (9.53 mm) pressure washer equipment in the industry and convert M22 metric thread size to standard National Pipe Thread (NPT) size for leak-free connections. Screw couplings are easily hand tightened and are ideal for connecting hoses together. Use Forney 75190, Replacement M22 O-rings, to ensure a leak-free seal.