7pcs Drill Bit Stop Collars Set Exact Hole Depth Bits Locator Drill Clamp Metric 3mm 4mm 5mm 6mm 8mm 10mm 12mm + 1pc Hex Wrench Used For:Fixed on the bit,Limit the depth of the drill holes 7-PC Drill Bit Depth Stop Collar w/ 1pc wrench; Drill Limited ring, clamping device, positioner Works with both standard and brad-point bits; Setscrew type collar will not damage bits Positively locks anywhere along the bit Hardened and Tampered High Carbon Steel Drills