A reducing coupling in a grooved piping system is designed to provide a restrained piping connection while reducing (or increasing) pipe sizes. It is a transition accessory to match different sized pipes through a single device. After the pipe ends are grooved, a rubber gasket that is suitable for the system is stretched over the pipe ends. The coupling segments are then placed over the gasket, and the nuts and bolts are fastened, resulting in a secure, and leak free joint.