Specifically designed for sharpening chainsaw blades. Silverline guarantees all hand tools for life and power tools for 3 years which means you can buy with confidence. File Diameter 4.0mm (see our other listings for the 4.8mm size) Quick and accurate sharpening. Attached guide plate holds the file at the correct depth. Clear markings allow easy alignment for common sharpening angles. Complete with safety handle for ease of use.