Reducing and equal bulkheads are made of Black and White Nylon and Gray Polypropylene. Barb sizes are 1/16”, 1/8” and .170” ID tubing. The external threads for panel mounting are 1/4-28” and a nut is supplied. The maximum supply pressure is 125 psi and the working temperature ranges are: -50˚ F to 180˚ F for Nylon and -40˚ F to 200˚ F for Polypropylene.