This pressure gauge has a connection diameter of 1/4 inch and is designed to measure pressures up to 400 psi (27.6 bar). It features a 2-inch face for easy reading of pressure levels. The gauge is designed to be connected using a 1/4" NPT connection size, making it compatible with various pneumatic and hydraulic systems. This product is suitable for use in industrial settings where accurate monitoring of air pressure is required.