These adaptors split out the S-Video signal (s-video male connector) into two coaxial signals (two RCA female connectors). This can make it easier to run the S-video sitnal long distances.
Sold in pairs.
Note: These adapters do not convert baseband NTSC video to S-Video, they simply "break out" the S-Video signal into its "Y" and "C" components so that it may be carried over less-expensive cables with RCA connectors.