Built into the lens barrel are two switches, one zoom lock that can hold the lens at any focal length and a manual focus override for when more precise control is required.It also has a minimum focus distance of 102.4" and a rotatable tripod collar. It is compatible with the Sigma USB Dock for focus microadjustment and firmware updates and comes with a lens hood, case, and shoulder strap.Works with Sigma's Global Vision line of teleconverters. Lens construction with 24 elements in 16 groups. Water and oil-repellent coating on the front and rear elements."F" Low Dispersion, or FLD, glass is designed with performance similar to flourite elements with a low refractive index and low dispersion for clearer and sharper imagery. Special Low Dispersion, or SLD, glass elements assist in providing greater clarity and contrast to an image. Nine rounded diaphragm blades for smooth out of focus elements. Maximum magnification ratio of 1:5. Front thread for accepting 105mm filters. It is 4.8" wide by 11.4" long. Eligible for Sigma's Mount Conversion Service.