The new teleconverters have been exclusively developed for the new Sigma lens product lines. Attaching the TC-1401 teleconverter between a telephoto lens and a camera increases the focal length by 1.4 times, while attaching the TC-2001 model increases it by 2 times. Both models feature SLD (Special Low Dispersion) glass elements that provide excellent image distortion correction. It is remarkable that one of the best glass materials is used for lens accessories. However, since Sigma aims for the best possible image quality, this is a logical development to meet the new "SGV" standards. The converters are dust and splash resistant, making them a durable construction for professional use. They are compact and lightweight, offering an easy way to extend the focal length range.