Original was round stainless steel. 3/32″ if my memory is correct.
Pumping action on any wobbler pump is by the space that appears at the intake side and proceeds around to the output side as the rotor wobbles. In other words, it takes a gulp of water on one side and moves it around to the output side where the space disappears, only to open up again for another gulp at intake. The tab has nothing to do with it except to separate the intake and output sides.
