LDG Electronics M-600 Remote Antenna Tuner Meters are optional analog units that provide accurate and precise metering of forward and reflected power, including SWR readings, when connected to AT600ProII Antenna Tuners. M-600's may be set to display a different parameter from the one displayed on the AT600ProII's built-in LED bar-graph. Both peak and average readings are available. LDG M-600 meters plug into the External Meter jack and is powered from AT600ProII tuners. These meters include an adjustable backlight. When your AT600ProII Tuner is not conveniently placed or is in a remote location, or if you prefer to view the needle movement of an analog meter, LDG Electronics M-600 Remote Antenna Tuner Meters are the perfect accessory!