I've bought this focus motor 3 times and sent it back each time. The engine was so loud that it was impossible to use it. Much louder than the Ronin S motors, which are nice and quiet. I think DJI may have made a bad batch and the sellers are trying to unload it here on Amazon. I called DJI every time I got one and they were of little help. I really wanted this to work as I love DJI products but the noise coming from this motor rendered it unusable. I've tried it with multiple lenses at a time, and even individually, and every time I turned the dial I heard a grinding noise.