Oregon 26831 3/8" Pitch 7-Tooth Standard 7 Spline Power Mate Rim Sprocket System Oregon 26831 Replacement Power Mate Sprocket System includes a drum with a replaceable rim, allowing the rim to be replaced.(Bearing 11893 installed) For 3/8" Pitch Chain Saws, 7-Tooth Sprocket, Standard 7 Spline (Sd7) Rim Sprocket System. Additional Oregon Components, Washer (26908), and Dust Cover (25047) sold separately Replacement schedule: Every three rims For use on Husqvarna Husqvarna: 61 (after S/N 0510572), 266 (after S/N 0510000), 268 (after S/N 0510000), 272 (after S/N 0510000) For use on Jonsered: 625 (after S/N 0510123), 630 (after S/N 0510000), 630 Super (after S/N 0510000), 630 West Coast (after S/N 0510000), 670 (after S/N 0510153)