For head bolts, brake caliper bolts, door handle screws, axle bolts and other applications. The 4 and 5mm bits have 5/16-Inch hex drive. The 6, 8, 10 and 12mm bits have 1/2-Inch hex drive. The 14 and 16mm bits have 5/8-Inch hex drive. The 18mm bit has a 3/4-Inch hex drive. The three largest sizes are designed to work on tamper-proof applications. Nine-Piece triple square 12 point bits to fit 4, 5, 6, 8, 10, 12, 14, 16 and 18mm sizes.