Sick of using that ballpoint pen to air down? An automatic tire deflator gives you a convenient way to air down your tire. The initial simple setup calibrates the deflators to your desired psi. That way, each time you use them, you just screw them onto your tire valve and walk away. Deflators release the air in your tire and stop automatically at the correct psi. No extra tools are required! Deflators easily disassemble for cleaning and are made from 100% brass material to eliminate rust.