Universal hose fittings are used for mating varying diameters of hose up to 1 inch. Sizes over 1 inch have a four lug design. Universal hose fittings are usually made from iron, brass, or stainless steel. They typically have a rubber seal for a leak-proof connection. Universal couplings are designed for use with air at pressures of 150PSI or less. Not for steam service. Always use safety clips.