https://www.youtube.com/embed/lQAm9OjV8iQ?rel=0
The eccentric placement of the rod through the brass face and
aluminum body ensures a large reference surface for square
registration. The short side can also be used when space is
restricted. As an added advantage, the eccentric face makes this
gauge less likely to roll off the work surface.
The Lee Valley URL for this year's AF entry:
http://www.leevalley.com/en/wood/pag...at=,75235&ap=1