High Quality Carbon Steel MaterialOur drilling depth limiter is made of durable carbon steel with black surface, rust and corrosion resistance, high hardness and not easy to wear and to distort. The tight form collar will stay strong when tightened and will not damage the bit. 8 Sizes of Limit RingsThere are eight different sizes of drill depth stops in the set, the sizes are 3, 4, 5, 6, 8, 10, 12, 16mm, which are compatible with most drill bits. Taking full account of your various needs at work, we can serve you well. Necessary for precise drillingThe drill stop ring is used as a mechanical collar. It can be used for any type of drill requiring precise drilling to avoid excessive drill penetration. The necklace can be firmly fixed in place and the drilling depth can be precisely controlled. It is repeat drilling Ideal for holes. With Hex WrenchA matching "L"-shaped hex wrench is attached, which has high hardness, high torque, good toughness and anti-skidding. After special treatment, the surface is smooth and the anastomosis is precise, which allows to better secure the drilling depth limiter. Wide range of applicationsThe double-wire hole has strong clamping force, which can firmly lock the drill. Please clamp the shaft in the correct position and take the necessary protective measures in the process of work wood.It is suitable for wood processing or other uses.