Digitrax Plug 'N Play Mobile Decoders with SoundFX control locomotive motor and sound functions. The 1 Amp decoder has all the LocoMotion features you expect from SoundFX too! Based on proven locomotive decoder technology, the decoder has preloaded sounds and can also handle downloadable sound. Supports the playable whistle feature with F2 key on DT400 throttles. Includes 28mm speaker. For complete control including lighting functions, use the FN04K1 Function Decoder with the SDH104 series decoder, or purchase the Combo Pack that includes the SoundFX decoder, 28mm speaker and FN401K1 lighting function decoder.