The relief pressures on a new series of relief valves from Industrial Specialties Manufacturing Inc., are easily identifiable by the color of the valve. Offered in 1/8 and 1/4 male NPT and 1/8 female thread, the valve housing is molded of polyvinylidene fluoride, an extremely stable and pure commercial resin. Special end sizes are also available. The internal relief material is nylon with a Buna-N seal.