Pixco 5mm C-CS Mount Lens Adapter Ring Extension Tube for CCTV Security Camera This is a "C" to "CS" mount lens black-aluminum adapter for all types of CCTV camera. A 5mm Adapter Ring attaches between lens and camera and converts a C-Mount Lens for use on a CS-Mount Camera. If you have CS mount on your camera and you have lens with C mount, you need the adapter to put between lens and camera. Compatible with: CCTV Security Camera