3/8" x 1/4"The nylon pipe bushings are designed specifically to insulate connections in water systems between piping of different metals, such as iron, galvanized, copper high copper content brass.
1301 Nylon Bushing
All thread sizes (3/8 x 1/4 to 2-1/2 x 2) of AquaTechnic Bushings are made with a heavy hex for wrenching. The nylon bushings are somewhat pliable and must be tightened securely. Also, the thread tapers are designed so that some flow of the nylon into inaccurate metal threads will occur if the thread size is within the specifications of the American Standards Institute.