715-A series solid aluminum optical breadboards are similar to 715 series breadboards. The difference is that in 715-A mounting holes are closer to breadboard edge (12.5 mm) and it has fifth additional central counterbored through hole which makes it possible to mount smaller breadboards on a single supporting element and in case with larger breadboards when fifth support is added the rigidity increases and the stress reduces when mounting heavy loads. All other specifications are same to 715 breadboards.