The answer could be that there is more then one DCC decoder that could work for your specific application. Also many decoders could be labeled for a particular scale such as then Digitrax DZ143PS (indicating Z Scale) or DH123D (Indicating HO Scale) or an NCE N14IP (indicating N Scale). In most cases you can use a Z or N Scale decoder in larger HO engines, in fact this is sometimes necessary to do in order for a decoder to fit!
The main factors to consider when choosing a decoder are:
What functions do I need?
What is the max stall current of the motor?
And do you want sound or the ability to add on sound?
And of course… will it fit?
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