This is a 90 degree angle unloader Pressure switch replacement part designed to work with Air Compressor. The pressure switch tells your compressor when to stop and when to start. There are multiple reasons a Pressure Switch could be leaking air. If it is leaking air the Pressure Switch should be replaced for a compressor to operate properly and safely. Additional Note: This is special design with 90 degree angle Unloader, please make sure the unloader position match with your old pressure switch