Test Marklin LokDecoder3 and SoundDecoder3 or any decoders using NEM 651, NEM 652, MTC14, MTC21 and PluX22 interface connections. Screw terminals are provided for testing other types. Features LED monitoring for peak signal for Aux 1-6, track input, Aux 3, and 4 amplified and not amplified, plus track connections for digital central controller (sold separately).