The Centering Scale Fence comes with each ProPack and All-In Pack.
The Centering Scale Fence allows the workpiece to be easily centered on the table. You simply measure the workpiece on the full-scale ruler then set the width on the half-scale ruler. The scale is only half the actual dimension so the piece is auto-centered without having to find center using more complicated means.
The Centering Scale Fence has both a metric scale and an inch scale.