8 PCS Drill Bit Stops with Allen Wrench SPECIFICATIONMATERIAL: Carbon Steel SIZE: 3mm/4mm/5mm/6mm/8mm/10mm/12mm/16mmPRODUCT FEATURES:? [PREMIUM MATERIAL]- 8 PCS drill stop bit set is made of high quality carbon steel, tough, sturdy and durable;? [8 SIZE DRILL STOP SET]- Assorted sizes are included in the package for various needs: 3mm, 4mm, 5mm, 6mm, 8mm,10mm, 12mm,16mm with an allen wrench key;?[FUNCTION]: Positively locks anywhere along the bit, screw type collar will not damage bits. Ideal for precise and repeated hole depths;? [WIDE APPLICATION]- The drill stop bit collar can be used on twist drill bits, brad point drills or any types of bit to prevent excessive drill bit penetration. Perfect for any job that requires high precision.? [EASY TO USE]- With the allen wrench provided in the package, it is quick and easy to make adjustment at any point on drill bit flutes / shafts. Great addition to your tool box.