The Canon EF 2x II Extender is a high-quality teleconverter that preserves the image quality of the lens it’s mounted to and multiplies its focal length by 2x. When combined with pro level EOS cameras & EF supertelephoto lenses with image stabilization, near imperviousness to weather extremes is achieved thanks to rubber gasket seals. Improved antireflective internal coatings also increase transmissivity & performance in backlit conditions.