Box contents: 1 x 1/4 inch pressure regulator compressed air (4 holes), with pressure regulator and pressure gauge according to EU standards, 1 x plug (can close a hole, which makes 4 holes pressure regulator to 3 holes, and leak-), 1 x adhesive tape High-quality material: The air compressor pressure control valve is made of high-quality metal material, which is strong and durable, not easy to damage and has good tightness Precise scale: The pressure regulator pressure gauge has a precise scale that makes it easier to read pressure values for setting and reading data Function: Thanks to the value on the pressure gauge, the valve can be used to adjust the closing and starting the air compressor Easy to install and remove: 1/4 inch pressure regulator can be ed directly onto the threaded interface of the compressor and other machines and is easy to install and disemble. conversion of 3 holes and 4 holes to meet your different needs