These valves attach to the pressure switch and bleed off or "unload" excess air in the lines and off of your pump head so your air compressor can easily start up. This is especially necessary after the unit reaches its max pressure and shuts off; the schrader valve is tripped by a lever on the pressure switch, which opens the valve and bleeds the air from the unloader tube and discharge tube. If air leaks from this valve constantly after the units shuts off, replace your check valve, not the unloader valve.
This item fits the following models:
15-pc Thunderbolt Black Oxide Drill Bit Set
1/4" x 50 Ft Noodle Air Hose with Coupler and Plug