GoolRC UDI UDI003 2.4G Wireless RC 20KM/H Racing Boat Speedboat with Transmitter Special anti-tilt function prevents tilting and keeps the boat sailing. Water-cooled motor extends the life of the boat. Built-in left and right navigation rudders enhancing sailing stability. Low-voltage alarm function: when the battery runs low, the transmitter will sound "Di,di,di". This warns that you have about 1 minute left, so you can sail it back for retrieval. Transmitter detects when 2.4G signal becomes weak and flashes an out-of-range light.