The Connect-6021 is for bidirectional connections between the former Märklin Digital System and the 60213-60215 Central Station. This allows you to control 80 locomotives (Motorola format as well as mfx) with the 6021 Control Unit, control locomotive auxiliary functions (function, F1 – F4), control solenoid accessories with synchronized display of their settings. This connection also allows you to use the 6043 memory as well as the memory functionality of the 60213-60215 Central Station. Connections on the back side: M-Bus cable (for connections to the 60213-60215). Side connections: Multi-pin strip connector for connections to the "6021 world". Dimensions 135 x 120 x 80 mm / 5-5/16" x 4-3/4" x 3-1/8".