The comm pad is the same as for X-wing pilots and TIE Fighter pilots just inserted (and curved) differently and with different markings.
The original prop was most likely vacuuformed in thin plastic, which made it pliable in both directions. This also means that the buttons on the original did not have very sharp features like on most replicas.
The comm pad has a large base (that fills the pocket), a raised rectangle and a raised square inside that where most of the buttons are. Two buttons and two recessions are outside the inner square inside the outer rectangle.
The raised square fits wholly inside the flight suit's window, and the other buttons are partially obscured. (some makers of flight suits make their windows long so that all buttons are equally visible when used for a TIE fighter or X-wing uniform, but that is wrong: the window is actually a tiny bit wider than it is long).
In the raised square, there are four buttons in a row, tight together. They are approximately 1/2"×3/4", or maybe a mm or two larger in each direction.
The "speaker grill" and the red button are about the same size. The square buttons are somewhat smaller and the button with the rectangular holes has the same short side but is a half side longer. (I.e. the pad in your image gets several things wrong...)
The innermost edge of the "speaker grille", the edge of the red button and the edge of one small square button outside the raised square are aligned on one straight line.
AFAIK, all buttons are the same height, about 2.5-3 mm.