Features Made of high quality ferrous metal materials, durable, suitable for air compressor, etc. Easy installation, low resistance, good sealing performance, reliable performance. Used to direct flow in one direction and prevent reverse flow in the piping system. It is often combined with a butterfly valve, sequence valve, etc. to form a one-way butterfly valve and a one-way sequence valve. The check valve is suitable for various liquids and gases, water, air and some corrosive liquids. Specification: Item Type: Check Valve Material: Iron Interface size: 1/2 inch Threaded Hole 1: Approx. 20 x 10mm/0.8 x 0.4inch (Outer Diameter and Inner Diameter) Threaded Hole 2: Approx. 21 x 12 mm/0.8 x 0.5 inch (OD and ID) Scope of application: Suitable for air compressors, etc. Package list: 1 * Check Valve Package List 1 x Check Valve