GMR 18 HD Sharpen your radar picture with high definition performance. The GMR 18 HD radar offers a whole new level of radar scanning capability. Physical & Performance: Unit dimensions, WxHxD: 45.7 cm diameter, 23.6 cm high ( 18" diameter, 9.3" high) Weight: 7.2 kg ( 15.8 lb) Waterproof: yes ( IPX7) Antenna sweep: 24/ 30 rpm ( dual rotation) Transmit power: 4 kW Power input: 10.5-35 V DC, 33.5 W Beam width: 5.0° horizontal, 25° vertical Maximum range: 36 nm Minimum range: 20 metres RoHS version available: yes Features: Garmin Marine Network™ compatible: yes High definition ( outstanding target separation with less screen clutter) : yes MARPA target tracking ( collision avoidance) : yes ( requires heading sensor; sold separately) Guard zone alarm: yes Additional: Connector with removable collar