K28RINGS is a Rolair ring set for the PMP22K28 pump assembly used in the 7722HK28 wheeled compressor. The kit comprises seven piston rings: three low‑pressure (LP) rings—31208760CH, 31208770CH, and 31208780CH—and four high‑pressure (HP) rings—31204700CH (two units), 31204710CH, and 31204720CH—as listed in the PMP22K28 parts catalog. Designed for rebuilding the PMP22K28 portion of the 7722HK28, this ring set restores the sealing surfaces between the piston and cylinder to maintain proper compression and compressor performance.
