What You Receive: you receive 4 x 3/4inch NPT Chicago fittings, 4 x silver safety locks and 4 x rubber washers, the quantity is enough to use, can meet your needs Pressure Grade: the recommended maximum working pressure is under 150 psi to prolong its service life Rustproof and Material: the universal 3/4 air hose is made of carbon steel, and the is galvanized, to prolong the service time Instructions for Use: each connector is equipped with a safety lock, which is applied to insert into the locking hole on the fitting to that the air hose repair end is connected correctly Widely Application: the universal air fitting can be applied to many occasions, such as pneumatic equipment, automobile industry, air compressors and mechanical engineering Please note: the physical slightly color difference or difference,please do not mind, thank you! Colour:Silver Material:carbon steel Package Contents: 4Sets * NPT Air Hose Fitting 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.