A pilot hole guide for drilling consistent 1/8" holes into the ends of 2x4 lumber (actually 3 ½" by 1 ½").

Two model versions: Align with the corner of the 2x4 or the sides of the 2x4.

Three holes: Middle hole is center and the two outer holes are spaced third of board's width.

Has a little ruler on the side divided into 1/8" increments.

Extrusions on either side to put up against the board being drilled, lining-up the holes to center. 

Supports shouldn't be required.