Sizes of Pacemaker Graphic boards, from "Graphic Graflex Photography", 11th edition, c1958:

"23" (2 1/4 X 3 1/4) board size 2 1/2" X 2 1/2"

"34" (3 1/4 X 4 1/4) board size 3 3/16" X 3 19/64"

"45" (4X5) board size 3 23/32" X 3 21/32"

These board sizes are the same for both Pacemaker Crown and Pacemaker Speed Graphics.

Len