The Nicholson round chainsaw file features an American pattern. It is precision engineered to provide maximum gram removal per stroke and amazing longevity. Always use with caution when working with chainsaws. 6 in. x 5/32 in. sizeAmerican pattern round chainsaw fileTighten tension on chain to firmly support cutters when filingFile from inside to outside of cutterPlace file against beveled cutting surface of teeth 20 degree to 45 degree with sawSharpen all left hand cutters on one side of chainThen move to the other side and file all the right hand cuttersCheck depth gauge height every 2 or 3 sharpeningsHeight between cutting teeth and depth gauge is between .020 in. to .030 inch