Especially for welding equipment piping with excellent durability and corrosion resistance. All piping connections from cylinder to torch can be associated with welding equipment by one touch operations. Body is chrome plated for better corrosion resistance, and plug is hardened for better durability. Oxygen and fuel gas fittings are different sizes and sleeves are given different colours, chrome plating for oxygen and copper plating for fuel gas, to prevent accidental interconnection. No oxygen types (1/4” and 5/16”) can be connected to fuel gas types (5/16” and 3/8”). However, respective types of the connection, oxygen plugs and sockets are interchangeable and fuel gas plugs and sockets are interchangeable. Female Threaded End Plugs and Sockets