Coyote Enterprises Automatic Tire Deflators provide an easy way to automatically deflate your tires to a precise pressure for any off highway driving. These tire deflators simply screw onto any tire valve and automatically deflate to a preset pressure. The automatic tire deflator is a spring loaded check valve with the ability to vary the spring pressure on the check valve via the Adjustment Cap. More spring pressure means a higher destination, shut OFF pressure. Less spring pressure means a lower destination pressure.