Dual flush push button Dual flush is certainly the way forward when it comes to concealed cisterns and this flush plate does exactly that. You may notice the two buttons on the front of the flush plate, one for a small, more economical flush, and one for a larger more powerful flush. Pneumatic Flush A Pneumatic flush is very similar to a manual flush, as you have to manually press a button on your flush plate. But what differenciates a pneumatic flush from a manual is what happens after you've pressed the button. Instead of rods activating the flush like in a manual, a special pneumatic pump is activated to push air through which triggers the flush.