Couplers and single-action joints are connecting parts used to attach and detach piping equipment such as pneumatic, hydraulic, water pressure, etc. Couplers are paired with the male on the insertion side and the female on the receiving side, and are attached and detached with parts of the same series. Connection methods include a lever-type fitting called a cam lock, in addition to a general ball lock method. Materials include steel, brass, stainless steel, etc. and for water it is made of brass or stainless steel, while for air it is made of steel. The product must be selected according to the pressure applied inside, the speed of the fluid, the thread size and the number of pitches. Couplers are available with packing, sealed products to prevent liquids from leaking from the joints, valveless valves that can be used for highly viscous fluids, and with nuts that can be directly attached to hoses, and you can select a product according to the operating environment and existing shape of the coupler.