The LokSound by ESU 21MTC Adaptor Board 3 is for adding a 21MTC interface by hard-wiring into a non-DCC ready locomotive. With its compact dimensions of 30.5mm x 15.5mm it is almost the same size as the decoder and also equipped with an extra mounting lug that can be easily broken off if not required. The board is equipped with amplifiers (about 250mA each) for the function outputs AUX3 through AUX6, which are only provided as logic outputs on all VHDM, NEM resp. NMRA compliant decoders. Thus the board offers the option of up to 8 outputs. The board includes 7-7/8′ 20cm wire leads connected to the most important contacts. Dimensions: Length 1-1/4 x 5/8′ 31.0mm x 15.5mm (With mounting tabs: 1-13/32 x 5/8′ 36.0mm x 15.5mm) The 21MTC Adaptor Board 3 is part of the broad assortment of ESU DCC accessories.WARNING: This product can expose you to chemicals, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov