450H is a continuous duty, hardmount compressor intended to directly fill tires or other items using a coil hose (not included). The 450H comes with a built-in, moisture resistant ON/OFF power switch. Features include a heavy duty stainless steel leader hose with a 1/4” quick connect stud for hookup to a coil hose and insulated wiring for simple installation. The function of a VIAIR “H” model compressor is to fill tires with the use of an air line and an open-end air chuck such as P/N 00025, 00027 & 00029. Please note, all air chucks used with “H” model compressors must be an “open-ended” type that allow air to pass through them freely. A close-ended air chuck will hold air back, which will damage the compressor and will cause the air line to rupture, which can cause injury. All “H” model compressors come with an onboard ON/OFF switch and are equipped with a stainless steel braided leader hose with an open-end quick connect stud installed at the end of the hose. This type of compressor does not come with a check valve, since it is NOT intended to fill air tanks. All “H” model compressors must be installed using the appropriate gauge wiring for the distance from the intended power source and must be properly fused to protect the unit and the vehicle it is installed inside of. All VIAIR compressors are equipped with a thermal overload protector that will shut down the unit when overheated. When cool, the compressor will automatically restart as normal.