This is a genuine OEM Otis RS5 remote serial board. These are also known as "RSL" boards. RS5 boards are commonly used inside Otis COP's and Otis hall fixtures/stations. Remote serial boards interface the controller with external buttons, keyswitches and jewels. Terminals on the RS5 board serve as I/O. These terminals can both receive a discrete input to send along the RSL link and also provide discrete outputs. Previous versions include: GAA23550D1 GBA23550D1 GCA23550D1 GEA23550D1 GFA23550D1 Parts may only be used and installed by certified licensed technicians