Vidpro MR-500 Motorized Focus & Zoom Shoulder Rig for Digital SLR Cameras Unique electric motor drive system offers seamless focus and zoom control Hand grips with integrated thumb switches allow users full lens control while maintaining a firm grip on both rig handles Variable-speed operation for precise adjustment during video recording Configurable lens ring rotational range limits and four follow-focus memory presets Includes 3 sets of gears to accommodate most lens sizes (70mm - 96mm outer diameter)