Getting tired of barely getting thru limbs with a lot of effort & very little sawdust. But from the shape of the teeth I knew a special tool was needed but had no idea what would do the job. Searched online & found a special file that does the job but no one in hardware stores had ever heard of one. Called a pruning saw file & I finally found a Stihl dealer to order it from. Had to convince him Stihl even made one. Nobody must ever sharpen their saws. Tool (Stihl #0000-882-0907 $16.00) came in today & sharpen 2 saws & discovered why nobody sharpens them. Its a job that requires patience. You can only sharpen one edge at a time & only push the file, not pull it on a backstroke. Each tooth has 2 edges & since the teeth are set, each side must be filed twice. I could prolly have bought 2 new saws for what I paid for the file but then I'd have a bunch of saws sitting around, as I never throw anything away. Anyway, that's another nagging little chore out of the way.