Defender security surveillance system Cable Extend Coupler 10pc for 4, 8, 16 ch This SALE is for a BNC Female to Female Coupler Adators for Samsung,Ideal for video survelliance installations to extedn short cables. It can join two BNC male/male cables together to make a longer cable It can also change the male connector of a BNC cable into a female connector BNC locking mechanism designed for the easiest, highest quality connection Precision machined, for maximum signal transfer and corrosion resistance