"The Sigma 150-600mm 5-6.3 DG HSM OS Contemporary was created around the concept of maximum portability meets utmost image quality in a variable aperture hyper-telephoto zoom lens. Light weight and compact, this zoom can handle any long-reach photographic situation one may encounter. This 150-600mm Contemporary boasts updated Sigma technology such as a quiet and optimized Hyper Sonic Motor (HSM) and a new Optical Stabilizer (OS) with an accelerometer for improved panning photography both vertically and horizontally, essential for birding, wildlife and motor photography. The Sigma 150-600 Contemporary also touts a new zoom lock switch that can be locked at any focal length and a new manual override (MO) switch is incorporated for improved focusing control. Working with the Sigma USB dock, this lens allows for maximum customization such as firmware updates and adjustments to the focus limiter, AF speed and OS view. TC-1401 1.4x Tele-Converter AF Equipped with 1 SLD (Special Low Dispersion) glass element for maximum image quality, the new Sigma Global Vision tele-converters utilize a splash and dust proof construction for long lasting durability. Created exclusively for the Global Vision lenses, these tele-converters ensure the utmost in compatibility, even for large diameter lenses. With effective AF at F8 and 1.4x the reach, get the most out of your Sigma lens. Incorporating SLD glass elements for better image quality: TC-1401 incorpo|First hyper-telephoto zoom from the Contemporary line|Lightweight and compact in construction for higher usability|Water and oil repellent coating on front glass element makes maintenance of the lens surface easier|Dust proof and splash proof mount"