Material: The drill bit retaining ring is made of high quality carbon steel, durable and reusable, it will stay firmly where you put it, not easy to slip or damage the drill bit. Various sizes: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm. Easy to use: Just select the appropriate depth limit drill, slide the limiter on the drill, set the desired depth with a ruler, and tighten. Do not spin the drill at high speed, it will lose balance. Drill Depth Control: Use the DCT Adjustable Screw Lock Ring with 8-Piece Drill Snap Ring to precisely control the depth of your holes; ideal for deep drilling when precise hole depth measurements are required; designed to Hold your bit in place and hold the full diameter of the bit without letting the screw touch the shank.