The hidden support is a very popular bracket configuration for breakfast bars and serving countertops mounted on knee (pony) walls. Designed specifically for use on a half-wall to create a floating counter, the Lincoln Top Plate hidden countertop support is 12" wide with a 3.25" mounting area. Multiple holes allow you to fasten the Lincoln Top Plate without hitting the nails in your framework.
Note: The size shown for the Lincoln is the length of arm extensions under your counter. The Lincoln has the additional 3.25" that mounts over the 2x4 stud wall. (Ex. Overall length of the 10x12 is 13.25")