Showing how to mark and drill the holes for DIY Shelf Brackets. When you order you will receive two black metal brackets and the holes guide. You will need a 3/8" drill bit and wood. The DIY Shelf brackets are 5/16" but a 3/8" hole is best. The wood can be a variety of thicknesses but at least 3/4" thick for best results You can use two on one long shelf.