TG3Z2910FCS-31 lens is a 2.9 to 8.2mm varifocal lens. Focal length adjustments can be made with a turn of the dial, virtually eliminating the cost and inventory problems associated with improper monofocal lens selection. This lens is a CS-Mount, comprised of all glass optics, come with locking setscrews and a durable metal barrel and mount, and are covered by a three year warranty. Aspherical optics provide excellent low light sensitivity