Drill bit depth stop collars: The drill bit collar set can be locked in any position of the drill, quickly and easily to help you drill the depth accurately. 8 sizes: including 8pcs drill depth stop set (3, 4, 5, 6, 8, 10, 12, 16 mm) and an Allen wrench to tighten the screw of each ring, used for helical drills, corner or any type of drilling . Wide applications: Depth stop drill bit is used as a mechanical collar, perfect for precise drilling, which is suitable for production and repeated drilling work, suitable for drilling wood or walls. Easy to use: Just select the appropriate drill bit depth stop collar set, slide the stop over the drill, adjust the required depth with a ruler and then tighten it. Don't run the drill at high speed - it's out of balance. High quality: Woodworking drill bit depth stop collars ring is made of high quality carbon steel, durable and reusable, will be firmly fixed at the place of placement, and is not easy to slide, does not damage the drill.