Specs: Bore Size: 56 mm. Includes: Piston, rings, pin and clips. Ethanol: Not compatible with greater than 10% ethanol fuel.. Replaces OEM Number: Husqvarna 503993903, 503993971. Fits: Husqvarna: 395 chainsaws. Stens one-year warranty ensures reliability and performance for every part. Stens branded parts are trusted by professional dealers to perform OEM quality repairs.