Proto Matrix 5 / M5 Paintball Marker O-ring Kit (2x or 4x Rebuilds) All o-rings are new and manufactured with high quality standards. O-rings are bagged per individual rebuild. Full List of included o-rings with placement where available comes with every kit. Sizing charts available for printout from the manufacturers (Orings-Online) website free of charge. Kit includes all o-rings needed to rebuild your marker. (This includes any and all regulators and parts shown in the original manual that are serviceable by the markers owner.)