The IDC System Zero XL1 Follow Focus for Nikon D800 is lightweight and compact Follow Focus system that features iDC's innovative gearless design for fast lens changes. The direct-drive follow focus wheel is machined from industrial plastic bearing material and has a soft, high-tech O-ring for positive rubber-on-rubber operation. There are no gear rings required! The simplicity of the rugged and ultra-lightweight SYSTEM ZERO allows the user to concentrate on the capture process without being distracted by cumbersome, heavy and generic equipment. The SYSTEM ZERO "slotted" Focus Plate offers a quick and easy way to align the Focusing Wheel Assembly with the focus ring on your lens - select the slot that lines up with your focus ring, slide in the Focusing Wheel Assembly, gently snug it up to the focus ring with just a bit of thumb pressure and tighten the Thumbscrew. It couldn't be easier! If any of the slots don't allow the wheel to make contact with the focus ring, the Focus Plate slides fore and aft to provide additional focusing wheel locations.