According with standard ISO 16028 No leakage: NWP4 Series couplings employ flush valving when connecting or disconnecting. This means that the valves are mated together so that only small amounts of fluid can be lost during disconnection or air inclusion during reconnection. Characteristics: Material: carbon steel or stainless steel for main parts Surface: zinc plated Sleeve: Hardened nipples and sleeves (steel) and solid bar stock construction make for a quality coupling with maximum resistance to damage from hydraulic and mechanical shock. Ball locking: Durable ball-locking mechanism assures each connection securely. A large number of locking balls distribute evenly to average the work load. Positive valve stop. The perch maintains valve alignment and provides metal to metal valve stop to ensure that the valves open fully, every time. Seals: Standard in oil proof NBR (Nitrile Rubber) and Polyurethane. Instructions: Material: carbon steel, zinc plated Valve element: poppet valve Seal: Std. NBR Retainer ring: PTFE Temperature Range (std. seals): -25 degree to +125 degree Special type: on request