Usage Tips:Rust-proof and durable material: Universal 3/4 air hose is made of carbon steel with galvanized surface for extended service lifePressure Rating: Recommended maximum operating pressure below 150 psi for extended service lifeInstructions for use: Each connector is equipped with a safety lock for insertion into the locking hole on the connector to ensure the air hose service end is connected correctlyWide range of applications: Universal air couplings can be used in a variety of applications, such as pneumatic equipment, automotive industry, air compressors and mechanical engineeringPlease note:There is a slight color difference or difference in kind, it does not affect the use, please do not mind, thank you!Colour:SilverMaterial:MetalPackage Contents:4 x NPT air hose fitting4 Pairs x silver safety locks4 x Rubber washersOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.