I purchased the MOVO MFF400 because I needed a better shoulder rig, and since this one offered variable speed motorized zoom and focus, I had to give it a try. It takes a little patience and ingenuity to set it up to fit it to your needs, but once you've tweaked it a bit, it's the best rig you can find for this price. My system includes the Movo MFF400, a Nikon D810, a 4K field monitor, a matte box, and a shotgun mic. With all of that equipment on the rig, it is necessary to purchase weights, which mount on the rear of the rig to counterbalance the weight in the front. Simply move the main controller as far forward as possible, then turn the shoulder pad around backwards and push it forward, almost touching the motor controller. Now you have room to mount the weights. I recommend purchasing Neewer brand weights. They easily slide on to the rig behind the shoulder pad. With all my equipment mounted on the rig, I use 7.5 lbs of weight, which places the center of balance directly over my shoulder, on the shoulder pad. Once you find the right amount of weight to put on the rear of the rig, you don't have to use much strength to hold it steady with your arms. This is easily customized to fit any videographer's needs. The motors are very powerful and the motor controls on the handles are extremely responsive and easy to use. You can change the speed of the zoom and focus by adjusting the dials on the handles. Move the main control module forward to mount the weights.