Designed to have dimensions clearly printed on the front and metric measurements on the back. easy to read. Sizes and units of measurement are clearly marked, so you never have to wonder what the tool is reading. While the tool can measure gaps on spark plugs, it can also be used as an electrode adjuster The small hole also allows you to easily attach your tool to your keychain so you always know where it is and have easy access to it. Wide measurement range, so you can be sure to get the correct calculation., Manufacturer: ZKLGS