The Sigma 300-600mm F4 DG OS | Sports is a revolutionary large-aperture ultra-telephoto zoom lens that delivers all the convenience and versatility of a zoom lens with the superior optical performance of an ultra-telephoto prime lens. With the Sigma 300-600mm F4 DG OS | Sports, photographers can move freely between focal lengths of 300mm and 600mm without changing lenses. The fast and precise AF performance of its High-response Linear Actuator (HLA)  and 5.5 stops* of optical stabilization at 600mm  make the Sigma 300-600mm F4 DG OS | Sports a powerful choice for the challenges of sports, action and wildlife photography, where situations change quickly and the opportunity for the perfect photo lasts only a few moments. Featuring a magnesium alloy body, thermal insulation paint and a number of additional features such as the newly added function ring, the Sigma 300-600mm F4 DG OS | Sports has been designed to support professionals achieve their best shots.