The VPH-2 Standard Optical Post Holder has a 2.0 in. (50.8 mm) height, and a spring-loaded brake shoe design which applies a constant force to 1/2 inch (12.7 mm) diameter optical posts even when the thumbscrew is loosened. This allows the orientation of an optical mount to be easily adjusted with one hand. This post holder is designed for standard posts, and has a 1/4-20 threaded hole in it's base.

Newport’s BUP-2 Universal Base incorporates a patented mounting device that gives unprecedented positioning flexibility. A freely rotating disk, inset into each base, has an eccentric clearance slot to accommodate a 1/4-20 or M6 tie-down bolt. This single bolt firmly clamps the assembly to your table surface. The slot permits 0.707 in. of translation — at least half the diagonal distance between holes in Newport’s English and metric tables, breadboards and mounting components like lab jacks and stages. Thus it is always possible to find a mounting hole through the clearance slot by rotating the trapped disc; the bases can be freely positioned anywhere, at any orientation, on your table surface.

(Information available on the Newport website)