... Alloy 2)low voice 3)needn't setting limit 4)intelligent control and stop-on-resistance ... AC,safety voltage.Radio receiver board built inside motor ,more reliable superheterodyne chip and strong anti-jamming ... ability. 3.Low voice :motor and the track system make low noise,runs ... control or group control. 6.Big torque:use the big torque AC motor with gear,running steadily quiet,MAX ...