Sharpening a chainsaw with a round file free hand is not easy. That's why most people who do this type of sharpening in the field or in the shop rely on a depth and angle gauge. This jig fits over the chainsaw chain and can mount to the chainsaw bar itself, and tooth by tooth it does the same basic job as the chisel and stone to return the beveled edge to the of metal or steel. To help ensure a good job, you can tighten the blade - just don't forget to loosen it afterwards. Next, check and see that the file fits the jig and the tooth of the blade. Replace the file after every 10 uses. The file gauge should come with instructions on the mounting procedure and use for that model of jig.