[Material] Drill retaining ring made of high quality carbon steel, durable, reusable, firmly fixed where you put it, not easy to slip, and will not damage the drill bit. [ Various sizes] 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm. Equipped with 1 set of limit rings (8 in total) and 1 Allen key. [Easy to use] Simply select an appropriate depth stop, slide the stop over the bit, set the desired depth with a ruler, then tighten it. Do not rotate the platform at high speed, it will lose its balance. [Drilling depth control] Use adjustable DCT screw lock ring with 8-piece drill split ring to precisely control the depth you drill; it is very suitable for deep drilling which requires precise measurement of hole depth; The drill bit is held in place and grips the full diameter of your drill bit without letting the screw touch the shank. [Wide Use] The drill depth limiter is used as a mechanical collar, which is very suitable for precision drilling, suitable for production and repeated drilling operations, and suitable for drilling wood or walls. Product size: the inner diameter is between 0.3 cm and 1 .6 cm, the outer diameter is between 0.9 cm and 2.4 cm, the thickness is between 0.3 and 0.4 cm, and the height is 0.8 cm. Shipping quantity: 1 set, including 8 rings, 1 small key