Optimized for Canon EF-mount lenses in the Global Vision line, the TC-1401 1.4x Teleconverter from Sigma will offer an increase in focal length of 1.4 times for select Global Vision lenses. This model offers full communication between the lens and camera and will allows autofocus to operate at up to f/8. The teleconverter also features one Special Low Dispersion element for reducing the appearance of chromatic aberrations and maintaining quality. Additionally, for protection, the TC-1401 is both dust and splashproof. When attached, the 1.4x conversion results in a light loss of approximately one stop. A soft zippered carrying case is included to protect the teleconverter when not in use. Lens construction features 7 elements in 5 groups Compatible Lenses: Sigma 120-300mm f/2.8 DG OS HSM Sports Lens Sigma 150-600mm f/5-6.3 DG OS HSM Sports Lens Sigma 150-600mm f/5-6.3 DG OS HSM Contemporary Lens 1 Year Warranty