Features: The YN-2.0X III is the updated version of YN2.0XII. Allows focal length of the EF increase to two times. Ultrahigh refractive index glass coating have raised the level of the teleconverter. The redesign of the upgraded electronic aspect make the auto-focusing function of teleconverter able to adapt to more lens, such as the EF70-200MM F/2.8 L IS II, the EF70-200MM F/2.8 L IS II USM and most of the lens can achieve automatic focusing. Suit for Below EF Camera Lens: EF 135MM F/2L USM EF 200MM F/2 L IS USM EF 200MM F/2.8 L II USM EF 200MM F/1.8 L USM EF 200MM F/2 L IS USM EF 300MM F/2.8L IS USM EF 300MM F/2.8L USM EF 300MM F/4 L IS USM EF 300MM F/4 L USM EF 400MM F/2.8 L IS II USM EF 400MM F/2.8 L IS IS USM EF 400MM F/2.8 L IS USM EF 400MM F/4L DO IS USM EF 400MM F/5.6 L USM EF 500MM F/4 L IS USM EF 500MM F/4.5 L USM EF 600MM F/4L USM EF 600MM F/4L IS USM EF 800MM F/5.6L IS USM EF 100-400MM F/4.5-5.6L IS USM EF 70-200MM F/2.8L IS USM EF 70-200MM F/2.8L IS II USM EF 70-200MM F/2.8L USM EF 70-200MM F/4L IS USM EF 70-200MM F/4L USM EF 300MM F/2.8L IS II USM EF 400MM F/2.8L IS II USM EF 500MM F/4L IS II USM EF 600MM F/4L IS II USM EF 1200MM F/5.6L IS II USM And you can use it with below cameras in Automatic Focus function: for Canon 5D, 5DII, 5DIII, 6D, 7D, 10D, 20D, 30D, 50D, 350D, 400D, 450D, 500D, 550D, 600D, 600Da, 650D, 1000D, 1100D. NOTE: 1, The shooting environment, resolution and the brightness should be ideal. 2, The AF Point should be adopted the free selecting focus mode. 3, For Canon cameras outside the list have not been tested. In generally, if the camera focus system is advanced, it can realize automatic focus. 4, When Teleconverter EF 2X is attached,the lens maximum aperture will be smaller by 2 stop.In the above two case, the camera will compensate the exposure auto matically. Specification: The Magnification: 2 times Coating: multi coating Lens composition: 9 elements in 5 groups Item size: 7.2 * 7.3cm / 2.8 * 2.9in(D * H) Item weight: 348g / 12.3oz Package size: 13 * 9.5 * 9cm / 5.1 * 3.7 * 3.5in Package weight: 439g / 15.5oz Package List: 1 * Teleconverter Extender 2 * Protective Covers 1 * Bag 1 * User Manual(Chinese & English)