After 25 years of rummaging through a box of scattered parts, I've finally put it in order. This holder is ideal for storing the most commonly used sizes. This product has been well made and supports them just right. Both sides of the holes were smooth with no nicks or jagged edges. The holes are accurate enough that they can also be used to size your bits. It has screw holes on the back so it can be hung on the wall, but mine sits right on my bench next to the abs.