Antenna Radio Test: No need to call for a radio check when you have this compact, easy to use, unit on-board. Unlike other meters in its class, the ART-3 tests receiver function as well as output power and VSWR (antenna efficiency). It is powered by an internal battery or can be connected to ships 12 VDC with the supplied power cable. Battery level can be checked at the flip of a switch. No serious boater should be without an ART-3. Specifications: Frequency Range: 155-158 MHz, RF Power Scale: 0 to 30 watts, Impedance: 50 ohms, Accuracy: 10%, Connectors: SO-239, Signal Generator: 3 KHz Deviation, Tone: 1000 Hz, RF Level: -115 dBM (approx.), Die-cast aluminum construction, Style 4079 one-meter cable available (sold separately) to connect the ART-2 or ART-3 to your VHF Radio.