Farmunion 7pcs Woodworking Drill Bit Depth Stop Collars Ring Positioner Drill Locator 7-PC Drill Bit Depth Stop Collar. Drill Limited ring, clamping device, positioner . Works with both standard and brad-point bits. Setscrew type collar will not damage bits. sizes:3mm 4mm 5mm 6mm 8mm 10mm 12mm