The Tilta Marking Disk For FF-T05 Follow Focus is an exact match for the marking disk that came with your follow focus. It fits snugly and features an indent that lines up with the locating pin, preventing the disk from shifting on the handwheel. You can mark the disk with focus points using a China marker or wet-erase marker (not included), and when it is time to move onto the next shot you can clean the marks from the disk.