And although it is a 12v pump, it works well on 4.8v - However, you MAY need to loosen the 4 screws on the bottom of the pump to get it to spin on 4.8v (I bought 4 of these pumps and 2 of them needed to be loosened - the other 2 worked fine out of the box)

BTW, here's a video of this smoke system on a YS 91:

[link=http://www.minnartist.net/Skybolt/Videos/skybolt_high_res.wmv]Skybolt w/ Smoke[/link]