$222.50
This is the front cap for the Graco Fusion AP spray gun. The Graco exploded parts diagram labels it as the front cap, Graco's service manual lists it as a retaining ring, and the Graco Partner Portal describes it as a cartridge ring cover. It is the piece at the front of the gun that covers the cartridge.
It fits the Fusion AP gun. Replace it when it no longer seats cleanly or shows damage. Fitting the genuine Graco part keeps the front of the gun to the factory specification.
Genuine Graco OEM part 15B211.
