The Canon EF 100-300mm f/4.5-5.6 USM lens is a telephoto zoom lens with a focal length range of 100-300mm and a maximum aperture of f/4.5-5.6. It features Ultrasonic Motor (USM) technology for fast and quiet autofocus. The lens has a minimum focusing distance of 1.5m and a maximum magnification of 0.19x. It is compatible with Canon EF mount cameras and is suitable for capturing distant subjects such as wildlife and sports.