6" x 16" Two Cavity Cinder Block

This is a standard size 6" x 16" CMU (Concrete Masonry Unit)

I modeled it at 1:1 scale so you'll have to scale it down when you print it, or you'll end up with a HUGE print on your hands.

It was modeled after the specs shown in a PDF from specblockusa.com:
http://specblockusa.com/downloads/gray-block/size-shape-2013.pdf

The actual modeled dimensions are 5 5/8" x 5 5/8" x 15 5/8" which is the actual size of a concrete CMU (3/8th" is left out for mortar)

The FreeCAD file for this mode