Esu decoder tester, part number 53900.
This decoder tester can be used to test electronic boards in the following formats: NEM651, NEM652, PLUX, NEXT18 and 21MTC.
Modules 53901 can be added for L, XL and servo-motor formats.
Associated with the ESU 53451 lokprogrammer, it allows programming of ESU brand decoders.