These Re-Usable Fittings are of heavy-duty construction and may be used over and over. These fittings are used when a more durable hose connection is required or when a clamped or crimped connection is impractical. May be used with either plastic or rubber hose. Mechanical: Hose I.D. and Hose O.D. must conform to the sizes listed. Slip and twist ferrule onto end of hose which has been trimmed square. No skiving necessary. Lightly lubricate fitting before inserting into ferrule. Tighten fitting into ferrule.