The practical HT644 Series 2.0 portable enjoys an IP68 (5 Meters for 1 Hour) rated construction, which means that they are dust protected and fully Submersible. Meeting MIL-STD 810C/D/E/F and providing commercial grade construction for tough, enduring performance. Entel's HT644 Series 2.0 portable conforms to stringent standards, enabling it to withstand the everyday rigours of shock, vibration and the corrosive effects of dust and moisture, ensuring many years of trouble free use. The HT644 Series 2.0 portable is supplied with the latest intelligent Lithium-Ion battery technology as standard. One key advantage of Lithium-Ion battery technology is the way it eliminates ‘memory effect’ meaning there is no need to fully discharge your battery before recharging. Therefore you are assured a full charge each and every time you take your Entel battery from its charger. The HT644 portable provides all INT, USA & CAN Marine channels.