For ideal results, place file against beveled cutting surface of the teeth 20° to 45° with saw and file from the inside to the outside of Cutter. Sharpen all left-hand cutters on one side of the chain and move to the other side and file all the right-hand cutters.
Came at the earliest estimated delivery date and was just what I needed to sharpen a small electric chainsaw chain. Have had trouble finding a 1/8" round file locally and was pleased to find these at a reasonable price.