Laser Zone™ — A unique coded laser — creates a grade control zone with all the advantages of satellite positioning technology, along with the accuracy of a laser. You get enhanced accuracies with the superior performance and usability of Topcon machine control. Your GNSS survey rovers can also use the Laser Zone for all site survey work and receive the same precision. Get multi-constellation coverage, millimeter-level accuracy, 8000 foot horizontal working range, 136 foot vertical working range and multiple-user capability in the shared zone. mmGPS is designed to be used simultaneously by multiple machines as well as survey crews, where every millimeter counts.