Rust-proof and durable material: Universal 3/4 air hose is made of carbon steel with galvanized surface for extended service life Pressure Rating: Recommended maximum operating pressure below 150 psi for extended service life Instructions 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 correctly Wide range of applications: Universal air couplings can be used in a variety of applications, such as pneumatic equipment, automotive industry, air compressors and mechanical engineering Please note:There is a slight color difference or difference in kind, it does not affect the use, please do not mind, thank you! Colour:Silver Material:Metal Package Contents: 4 x NPT air hose fitting 4 Pairs x silver safety locks 4 x Rubber washers Only 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.