Waterproof “original” authentic “smart” version with quality assurance (the only official version). 20mg is suitable for the model aircraft, car model 1:10 and 1:8 models: flat cars, suvs, short bigfoot trucks, cars, climbing, simulation models, gasoline engines, robots, mechanical arm, aerial, multi-axis gear, compatible with all mainstream JR/FUTABA remote control equipment microcontroller, etc