This amazing product designed by Midlands Vinyl is going to make marking your cups a breeze. The wingnut on the side can be adjusted so that you can slide your pencil holder up and down. The black pencil holder can also be tightened to hold your pencil or marking tool steady. There is a video in our teaching group Tumbler Mayhem & More that shows how to use this. We will work on getting a video put up here on the website.