Made from Rigid HDPE Polyethylene this drill and tap index is durable and will last a life time. The first row holds taps 4-40, 6-32, 8-32, 10-24, 10-32, and ¼” – 20. Second row holds drill bits recommended for use to drill the pilot holes for the corresponding tap in the first row: #43, #36, #29, #25, #21 and #7. Third row holds the close fit through hole bits corresponding with the screw sizes of the first row: #32, #27, #18, #9, #9, #F.