180mm macro lens with f/3.5 maximum aperture for Canon SLR cameras. 3 UD glass elements and internal floating system combine to minimize aberrations. Advanced ultra-sonic monitor (USM) for high-speed, quiet autofocusing. Focusing distance range of 1.57 feet to infinity; supports EF Extender 1.4x and 2x. Measures 3.2 inches in diameter and 7.3 inches long; weighs 2.4 pounds