Thank you for viewing. I am selling these items as I am retiring from Mini 4WD. This is a hole drilling jig for roller installation by SKW. It is a set of 3 pieces: 101mm, 102mm, and 104mm. The 102mm is unopened. The 101mm and 104mm have been used, and the numbers are written on them. There are no problems with use. Please refrain from purchasing if you are nervous or if you are looking for a new item. Also, please purchase only if you can research how to use it yourself. SKW Jig Mini 4WD Roller width