The GPO FLAGMASTER 1800 is equipped with two different flag-finding technologies to assure a flatlock distance can be acquired. This unique system will first look for the reflective prism located at the top of the golf course flag pin. If that is not available, the FLAGMASTER 1800 will convert to a close-target distance function. This dual system assures a flatlock distance every time. LOS (line-of-sight) and SLOPE modes are also integrated into the FLAGMASTER 1800. The LOS mode will measure the exact distance to your target. The SLOPE mode provides both the angle of the target and the adjusted distance to the target. SLOPE mode is designed to help you adjust your swing for angle compensation. The slope function of this new rangefinder also features red flashing LED lights when this mode is turned on, notifying course judges that the device is in a no regulation mode.