Pocket-sized gauge for quick and easy identification. Useless unless there are instructions. Hopefully a printable PDF The measuring tool is perfect for someone with a pile of chains and bars to sort through. Problem for a non professional like myself is, I need an explanation on some of the tool markings. Most of the tool is self explanatory, but a couple marks need identification. Measures the chain pitch, bar groove width, chain gauge and file size. Fits in a wallet or can be used as a keychain. Helps determine the correct tools and accessory dimensions for chainsaw maintenance. Red color makes it easy to find in a tool box.