Smooth running, superb sound by ESU, and nice detailing highlight this beautiful little locomotive. We do a little running featuring two of the new Atlas ALCo S2's. These locomotives have factory installed sound provided by an ESU LokSound Select 21 pin decoder. We added a TDS SuperSonic speaker to each of the locomotives to bring out the superb sound of the LokSound decoder. The cab does not have an interior, so fitting the additional speaker was very easy.