UDI U002 2.4GHz High Speed Big RC Racing Boat - Green Comes equipped with a water cooling system to prolong the life of the boat Advanced 2.4GHz automatic code pairing technology allows you to control different boats use different frequencies. When the 2.4G Signal becomes weak, the transmitter will detects and flashes an out-of-range light. Capsize recovery function - The self-righting feature lets you command your boat back into action if it capsizes. Low voltage alarm - When the battery runs low, the transmitter will sound "di, di, di" this warns you about 1 minute left, so you can sail it back for retrieval