This White Paper describes the operating principle, technical details, and performance of the Menlo Systems ORS Ultrastable Laser System. It gives a general overview of applications for ultrastable lasers, with specific use cases of Menlo Systems’ ORS systems. A more detailed presentation of an application using a novel approach for clock comparisons [1] demonstrates the capabilities of a commercial ultrastable laser system to perform state-of-the-art measurements, and the potential for future field applications