The SJ Bridge has three Econet sockets on the top.

The purpose of an Econet Bridge is to join two networks together, so the Bridge is plugged into a socket box on each network as if it were an Econet Station.

The two networks are known as Network A and Network B, but they are each allocated a unique number in the range 1-127.

The rightmost socket is used to connect the Bridge to Network A.

The two leftmost sockets connect the Bridge to Network B. The Bridge can generate a clock so Network B does not need its own clock box. If the Bridge clock is used, then the two leftmost sockets are used to connect the Bridge to Network B as though it were a clock.

If Network B has its own clock, the internal Bridge clock must be disabled and only the middle socket is used to connect the Bridge to Network B.