The 3 male thread connectors are respectively for tube connecting, air pressure tank and compressor piston pump, it is easy to install with the thread connecting ends.Air compressor check valve has compressive strength, good corrosion resistance, high performance and high reliability, it is great to replace the old or broken parts.Made of high-quality brass materials, this check valve is durable and anti-corrosion.The valve is 4.2cm long and 3.9cm wide. The 3 thread diameters are respectively 9.5-10mm, 16-16.5mm, 20-20.5mm, the external thread size is 1/2-inch and 3/8-inch, the hexagon head size is 18mm.It is a good replacement for old or broken check valves in air compressors.Item Name: Check ValveMaterial:BrassThread Size: 9.5-10mm, 16-16.5mm, 20-20.5mmExternal Thread Size: 1/2, 3/8Hexagon Head Size: 18mmSize:4.2cmx3.9cmx3.9cm/1.65inx1.54inx1.54inNotes:Due to the light and screen setting difference, the item"s color may be slightly different from the pictures.Please allow slight dimension difference due to different manual measurement.Package Includes:1 X Check Valve About Shipping: All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances.Any questions, please feel free to contact us During the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours, wish you a happy shopping Thanks for your cooperation and we'll make you feel satisfied.