Genuine Stihl chain tensioner assembly from donor MS 290/310/390 saw. Includes tensioner housing, threaded adjuster screw, worm gear, chain catcher/guide, and mounting hardware. Fully functional—screw turns smoothly, gear engages properly, no stripped threads or broken parts.

Normal used patina/oil residue (cleanable), no major damage. Pulled from donor.  perfect match for chain tension rebuild or replacement on these popular mid-size saws.

Photos show exact tensioner (housing, screw, gear, catcher). Sold as-is (used donor part), no returns, but message with questions or for tension test photos before buying.