This is a bezel/mounting frame for the Sparkfun COM-07835 / Adafruit 1611 4x4 button pad. It's a one-piece alternative to the combination of two Sparkfun COM-08747 bottom bezels and two Sparkfun COM-08746 top bezels and is thicker (6mm vs. 1/8") so that the heads of the 4-40 cap screws are hidden in the counterbores. You can use a laser or die cutter to make a faceplate to glue over the front and hide the screws - after you've assembled and tested everything, of course!