Piston Ring Std / Husqvarna 503 28 90-15Pack Size:1Husqvarna 503 28 90-15, Husqvarna 501 51 12-01, Husqvarna 501 51 12-03Ahlborn FOR-6338Husqvarna 261, 262, 362, 35, 61 chain sawsCylinder Diameter: 48 mm, Ethanol: Not compatible with greater than 10% ethanol fuel, Packaged in reusable protective polycarbonate case