From the ManufacturerDesigned to extend a lenses focal length by a factor of 2x, the redesigned Canon Extender EF 2X III delivers optical performance on par with the finest Canon super telephoto lenses. It features a built-in microcomputer for seamless communication among camera body, lens and extender, features careful lens placement and coatings to minimize ghosting, flare and chromatic aberration, and even has a new Fluorine coating that keeps soiling, smears, fingerprints to a minimum. Extender EF 2X III meets necessary standards in terms of rugged, dustproof and water resistant construction, and should be in every professional's camera bag.Technical Specifications Focal Length & Maximum Aperture Magnification: 2.0x Lens Construction 9 elements in 5 groups Max. Diameter x Length, Weight 2.8 x 2.1 in, 11.5 oz / 72.0 x 52.7mm, 325gProduct DescriptionThe Canon Extender EF 2x III is designed to extend a lenses focal length by a factor of 2x, the redesigned Canon Extender EF 2x III delivers optical performance on par with the finest Canon super telephoto lenses. It features a built-in microcomputer for seamless communication among camera body, lens and extender, features careful lens placement and coatings to minimize ghosting, flare and chromatic aberration, and even has a new Fluorine coating that keeps soiling, smears, fingerprints to a minimum. Extender EF 2x III meets necessary standards in terms of rugged, dustproof and water-resistant construction, and should be in every professional's camera bag.