YONGNUO EF 1.4X III Teleconverter Extender Auto Focus Lens for Canon EOS EF Lens Yongnuo Extender EF 1.4X III - Front & Rear Caps - 1 Year Warranty Compatibility: Canon EF mount(Electronically controlled) Lens construction: 9 elements in 5 groups Dimensions Diameter X Length: 2.2 x 2.9" / 55  73.9mm Weight: 12.1 oz / 342 g