This is a drill bit index for 1/16" to 1/2" drill bits in 1/64" increments. The back is beveled with cutouts to fit perfectly and angled against a pegboard as shown in the picture. Two standard pegboard hooks will be needed for to mount it on pegboard. Screws could also be used to mount it to any vertical surface. Note: It cannot sit on a flat surface by itself without tipping over due to the slanted back. Drill bits with a full sideboard do not fit in this index , if they are larger than 3/8". The holes are oversized by 1/64" and have beveled edges to make it easier for drill bits to fit.