LokPilot 5 Micro DCC-Only Control-Only Decoder by ESU is a great choice for N and TT Scale locomotive models. LokPilot 5 DCC-Only supports DCC and will NOT support operation on analog AC systems. It offers a choice of 14 through to 128 speed steps, two and four-digit addresses in DCC format and up to 32 functions. On RailComPlus(R) systems the decoders register themselves automatically on command stations equipped with the feature. This decoder is dual-mode and can operate on standard DC railroads. The LokPilot 5 Micro DCC-Only Control-Only Decoder has a footprint of only 5/16 x 9/32" 8.0 x 7.0mm and a thickness of only 3/32" 2.4mm (on the capacitor:1/8" 2.9mm). PluX16 and Next18 interface versions are slightly larger at 1/2 x 3/8" 13 x 9.2mm.