Carbon steel material: Woodworking drill bit depth stop collars is made of high quality carbon steel, the surface is blackened, rust and corrosion resistant, high hardness, not easy to wear and deform. Use: Drill depth stop for drill bits used to precisely control drilling depth when drilling holes in wood to avoid material waste. 8 sizes: Depth stop ring consists of 8 pieces of 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm and small keys. Different specifications can meet different needs. Screw fixing: Attach drill bit to collar depth stop by tightening screw. The good grip of the screw can prevent the stop ring from slipping and achieve precise drilling depth. Easy to use: Just place the limiting hole in the appropriate position of the drill bit, then tighten the screw to fix the limiting ring, operation is simple and convenient. When drilling, the required depth is always exceeded unexpectedly. How to use effective force without overdrilling? is our solution! The drill stop kit fits most drill bits and can be easily adjusted to the exact depth required. While avoiding over/under drilling, it immediately presents holes of equal length and precision. The drill bit has built-in screws that can help you adjust the size and pressure used to tighten the drill bit without damaging the drill bit. The Allen key will help adjust and install/uninstall the cap and can also be used for any other projects. Multiple size options: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm. Compatible with any torque drill for wood, metal, concrete or masonry with hexagonal fixing screws. In jobs where precise drilling is required, it is cushioned to avoid errors and wasted material. How to use: 1) Slide the correct size stopper to the required depth into the drill bit. 2) Align the locking screw with the ground (main body). 3) Tighten the lock screw with the wrench provided. Note: 1. Make sure the nut screw is firmly attached to the center of the flat part of the drill bit and tightened. 2. Do not perform exercise at high speed because he will lose his balance.