The DCC91 is a direct plug 21 pin decoder.
Gaugemaster DCC91 Ruby Series 2fn Standard DCC Decoder 21 Pin
DCC91 Gaugemaster Ruby Series 2fn Standard DCC Decoder 21 Pin
Gaugemaster DCC90 Ruby Series 2fn Standard DCC Decoder 8 Pin
DCC90 Gaugemaster Ruby Series 2fn Standard DCC Decoder 8 Pin
Gaugemaster DCC93 Ruby Series 2fn Small DCC Decoder 6 Pin
Gaugemaster DCC92 Ruby Series 2fn Small DCC Decoder 8 Pin
