The diamond coated Cdisc file is a 4mm (5/32") diameter file. The teeth of the 4 tooth Cdisc and 6 tooth Herd Boss are coated with tungsten carbide and because of the hardness of this material the diamond coated Cdisc file is required to sharpen the teeth. A standard chain saw file just won't work. You can also use the he Diamond Coated Cdisc File for our 8-tooth goat trimming disc as well as keeping your manual hoof knife nice and sharp.