The Nakajima hose coupling has no female or male ends, removing the trouble of matching different ends. It is easily connected or disconnected with a quarter turn using the proper coupling spanner. Reducing couplings are used to connect hose fittings of different diameters. The common reducing coupling options are 2.5” to 1.5” and 2.5” to 2.0”. Made to Japanese Industrial Standards (JIS).