C mount types lenses are usually found in CCTV & photography equipment, they provide a male thread with a female tread on the camera side, The focal distance for these lenses is 17.526 millimeters (0.6900 in)
The CS mount type lens have a focal distance of 12.526 millimeters (0.4931 in), CS-mount lenses are built for the smaller formats, 1/2 inch and down. therefore the need for an adapter when using this type of lenses in older cameras
Security use cameras produced after 2012 likely are CS compatible. Any CS lens compatible camera can be adapted to C mount using a C mount adapter.