Canon Extender TeleConverter 2.0X MK II

The EF 2X II doubles the focal length of any lens it's mounted to, and reduces its effective aperture by two stops. Attaching this high-performance extender to a 135mm or longer lens, or to the EF 70-200mm f/2.8 L boosts the focal length by 2 times. With seven elements in five lens groups, it preserves the prime lens' image quality.

With the extender attached, the f-number decreases by two stops. Auto focusing is possible with lenses whose maximum aperture is f/2.8 or faster. This latest version (MKII) is dust and water resistant for increased system protection.