An industry first! Century's user-markable white Delrin focus scale and witness mark that facilitate accurate and repeatable focusing. The unit simply clamp mounts over the lens' existing focus scales, no lens modification required. The effective lock-out mechanism limits the lens' focus range to 3-feet to Infinity with hard limit stops. Also included is an industry standard-pitch follow-focus gear to facilitate integration with popular professional cine-style follow-focus systems.