This is a tool for accurately drilling an 8mm hole. The tool is a carrying drill guide with the dimensions: inner diameter - 8mm, outer diameter - 22mm and thickness about 7.5mm. The drill guide has eight internal hole dimensions with a diameter of 22.2mm and a depth of 8mm. You can watch the video here: https://www.youtube.com/watch?v=RZjch_Od4M0