M-Style® Coupler and Plug Kit includes one 1/4 in FNPT coupler and one 1/4 in MNPT plug. Made up of a brass body, brass sleeve coupler and steel plug. With a 1/4 in basic flow size and air flow of 40 scfm, this coupler and plug combination has a maximum pressure of 300 psi and a Buna-N seal.