Thanks for the comments guys!
T, the box is a Wave2k center model unit, basically a wavemaker/box (enter 'wave2k' into google for more info). The large (quite large) motor sits outside of the tank and spins the belt. The top and bottom alternative flow, which gives a wave like flow. It's does a phenomenal job and I love it to death. Puts out an impressive 4000gph and adds no heat to tank. The fish love to play in the flow. It is strong though, and in the FTS you can see it's impossible to keep sand in the very front center.
It makes the most realistic flow I've seen in a tank. Here's some Xenia in the flow, before my Blueface mowed 'em down:
www.youtube.com/watch?v=mecg-dz_TAM