Great product and price is best around
Used it to get my idle settings and high speed screws set on a pair of rebuilt 391 Stihls. Set idle right at 2850 rpm and high speed at 11800-12200. A little less than the 13000 rpm max but saws run sound and respond amazing thanks to this nifty little tool. Best part just hold it close and it gives you a reading. Takes the guesswork out and eliminates ear test
Better than hand filing a saw. Files drags and the tooth at the same time. Will be buying more sizes.