I bought two of these flight controllers and none of them work! Powered by a matte 100mm quad and both FCs have 1 of 4 unpowered motor ports. The second has the engine number m4 and the first one I bought was without electricity per m2. If you buy, do not waste time and use a voltmeter to check that the motor pads are powered before installation. Seemed like a good buy at $17, now disappointed after spending $34.