It comes with two sprocket belts so I have one sprocket on the zoom ring and one sprocket on the focus ring. I use it with a Nikon 70mm 300mm lens and it has no trouble focusing or zooming smoothly. The only problem I have is that if you install it with Zhiyun TransMount Image Transmission HD Video Transmitter 2.0, you won't be able to balance your Weebill S together if it's too heavy, and your Weebill S front becomes too heavy. Otherwise it works great!