Extender EF 2x III: w/ Case LP811; For EF 70–200mm f/2.8L IS III USM, EF 70–200mm f/2.8L IS II USM, EF 70–200mm f/2.8L IS, EF 70–200mm f/2.8L, EF 70–200mm f/4L IS II USM, EF 70–200mm f/4L IS, EF 70–200mm f/4L, EF 100–400mm f/4.5–5.6 IS II USM*, EF 100–400mm f/4.5–5.6L IS*, EF 135mm f/2L, EF 180mm f/3.5L Macro, EF 200mm f/2.8L II, EF 300mm f/2.8L IS, EF 300mm f/4L IS, EF 400mm f/2.8L III USM, EF 400mm f/2.8L IS, EF 400mm f/4 DO IS II USM, EF 400mm f/4 DO IS, EF 400mm f/5.6L*, EF 500mm f/4L IS II USM, EF 500mm f/4L IS, EF 600mm f/4L IS III USM, EF 600mm f/4L IS II USM, EF 600mm f/4L IS, EF 800mm f/5.6L IS; *In most cases, autofocus is disabled if extender is combined with this lens. All other lens functions work normally.

Designed to extend a lenses focal length by a factor of 2x, the Canon Extender EF 2X III delivers optical performance on par with the finest Canon super telephoto lenses. It delivers seamless communication among camera body, lens and extender, and features coatings to minimize ghosting, flare and chromatic aberration. The Fluorine coating resists soiling, smears and fingerprints. Extender EF 2X III meets all necessary standards in terms of rugged, dustproof and water-resistant construction, and should be in every professional's camera bag.