Vivitar 2x DG Teleconverter (4 Elements) for Nikon AF & AF-S, 80-400mm f/4.5-5.6G , 800mm f/5.6E, 200-400mm f/4G, 300mm f/2.8G, 70-200mm f/2.8G, 200mm f/2G, 105mm f/2.8G, 300mm f/4D, 500mm f/4G, 70-200mm f/2.8G, 600mm f/4G, 400mm f/2.8G, 300mm f/2.8G , 200-400mm f/4G Lens and more Doubles Focal Length of Existing Lens. This teleconverter is a portable, high-quality and versatile accessory that's well worth having in your camera bag. 4-elements. Multi-coated Optical Glass. with anti-reflection coating Teleconverter will increase the focal of 300mm lens to 600mm. This teleconverter will maintain aperture control, manual/auto/program/etc., with all AF-AFS autofocus NIKKOR lenses.