8 sizes: 8 different depth stops, the box contains 8 different depth stop rings (3, 4, 5, 6, 8, 10, 12, 16 mm), which can be used for different types of drills, and a hex wrench. Sustainable: The carbon steel stop ring is made of high quality carbon steel, which is durable and has a long service life. It will precisely control the depth of the hole you drill. Widely Used: The drill stop ring is suitable for repeated drilling operations, suitable for twist drills, wood drills, angle drills, etc. It can be used for drilling wood or drilling walls. High quality material: Carbon steel stop ring; the center of the pin is stainless steel. Wear-resistant and corrosion-resistant, it is a good tool for woodworking and wood crafts. Method: It is mainly used to set the limit drilling depth on the drill bit and precisely control the depth of the hole to be drilled. It is not only suitable for standard drill bits, but also for curved head drill bits. The fixed screw collar will not damage the bit. Material: carbon steel Color: black Overall length: M3: Internal diameter: 3mm / 0.1 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M4: inner diameter: 4mm / 0.1 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M5: inner diameter: 5mm / 0.2 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M6: inner diameter: 6mm / 0.2 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M8: inner diameter: 8mm / 0.3 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M10: inner diameter: 10mm / 0.4 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M12: inner diameter: 12mm / 0.5 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch M16: inner diameter: 16mm / 0.6 inch, thickness 3mm / 0.1 inch, height 8mm / 0.3 inch Package includes: 1*M3 1*M4 1*M5 1*M6 1*M8 1*M10 1*M12 1*M16 1*hex key