The relay adapter box converts the ST-7/8/9/10/2000 electronic relays to mechanical relays. Most commercially available mounts such as those from Software Bisque, AP, Meade and Celestron do not require mechanical relays, but others, such as the classic Losmandy G-11 do require some other form of electrical isolation between the camera and the mount. If you are not sure, check with your mount manufacturer. A special camera to adapter box cable (not shown) provides the 12VDC needed to operate the relays.