For quick testing of the new Märklin LokDecoder3 and Märklin SoundDecoder3, as well as all other decoders that use the following interfaces: NEM 651, NEM 652, MTC14, MTC21, PluX22, and NEXT18. Other decoders, such as those for gauge 1, LGB, or with individual wires, can be connected via screw terminals. Additional features include: LED monitoring for the front signal for Aux 1-6, track input, Aux 3 and 4 amplified and unamplified, track connection for the digital central unit, speaker, motor, separate connection terminals for an additional motor, and direct connection to the Märklin decoder programmer.