Feature:This is an air dryer purge valve. This is the common problem with the Air Dryer. Just unbolt the old purge valve and replace with this new purge valve. Just bolt the three bolts in and replace the filter/cartridge on topPart type: AD-9 Air Dryer Purge VavleReplace part number: Replacement for Bendix 800405 5004341Compatible Models: AD-9 Air DryerPackage Includs:1x Air Dryer Purge Valve with Heater as the picture shows