It's all too easy to lose track of beam rotations when youre winding on a warp, and miscounts mean wasted yarn or worse. Our Revolution Counters take-on the memory work so you can focus on the creative work without coming up short. Counters can be used with any tension box track arm. Newer track arms come pre-drilled for revolution counters. If you have an older system, you can either drill holes using the instructions included with your product or purchase a new one that is pre-drilled (please see this listing here).