This PROMAX piston seal replacement kit is to be used on the old style (round cylinder) and new style (rectangle Cylinder) compressors on RG5410 series, MiniMax Series and PROVAC Compressors. Kit includes all necessary parts to rebuild the piston "SLYD" Rings, Square piston seal and cylinder seat seals. Use caution not to disturb the head or valve plate when disassembling the upper end or the seals will need replacement.