The Sigma 100-400mm f/5-6.3 lens is an compact ultra-telephoto zoom lens with a filter size of just 67mm and weight of just 1,160g. Yet it also comes with the full range of features and functions expected of an ultra-telephoto zoom: optical stabilizer (OS), hypersonic motor (HSM) with updated algorithm for fast autofocus, focus limiter, and more. In addition, this uncompromising specification becomes customizable with the available SIGMA USB Dock accessory.