while scoping out the TAS site, i was rather draw in by the ‘new’ smoke unit that will ‘Puff’ for every ‘Chuff’ of a steamer…sounds as if it is an almost exact duplicate of the ‘new’ aristo smoke unit…except the retail…man, talk about sticker shock!!! :^0 70 bucks and you too can make your Pacific, Pacifikado, LGB hudson/mikado, even a little porter loco belch out smoke in synchronized ‘Puffs’…BUT, this TAS has thought ahead of the game! :^) you do not HAVE to buy a $70 fan driven smoke unit if you already have any of aristos FAN DRIVEN SMOKE UNITS (i believe aristo is the only CURRENT manufactuer of these in ‘G’ scale). TAS also sells just the circuit board, about the size of a square quarter with a couple of wires hanging off of it…will make (according to the TAS website) ANY (except TMCC) FAN DRIVEN SMOKE UNIT a “Puff 'n Chuff” smoke unit for under $40!!! :^D as for it working on the MTH Hudson/Challenger, it wont, but then again, those engines already have their own 'puff n chuff smoke systems, so why spend money on those locos??? apparently, the smoke unit gets its signals from a sierra or phoenix soundboards, to “Puff”…i think it will work with any sound system actually, as long as there is a reed/magnet to generate the sound systems ‘Chuff’ sound…MTH takes the power from the motors for their version, NOT from their sound system…and for some inane reason, not on TMCC either…dont really know how that will effect the Scale Command market for ‘G’ scale tho…anyone have/used this latest large scale offering yet???