Gast K478 service/rebuild/repair kit used on oil-less "Q" models with internal filtration (i.e. 1023-101Q-SG608X). Service kit returns your unit to original factory performance specifications. Recommend for service every 2 years. Important: Use Gast AH225D flushing solvent to flush debris from pump when servicing unit. Service kit includes: (4) AK513 Vanes, (2) AK526 Filter Assemblies, (2) AK473 O-Rings, (2) AK510 Endcaps, (1) AK522 Gasket and Instructions.