The E-T-A Engineering Technology part 12-J20-20 is a circuit breaker mounting socket that is designed for use with the 1170 Series. It features a two-way mounting configuration, making it versatile and easy to install. The socket is equipped with 6-32 UNC screw terminals, ensuring a secure and reliable connection. It is an essential component for any electrical system requiring circuit breaker installation, providing a convenient and efficient solution for mounting and connecting breakers.