[Material] The drill stop collar is made of high quality carbon steel, durable and reusable, it will hold firmly where you put it, and won't slip easily or damage the drill bit. < p >Various sizes: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm, 16mm. Comes with 1 set of drill limit rings (8 pieces in total) with 1 Allen key. [Easy to use] Simply select the appropriate depth stop drill bit, slide the stopper into the drill, set the depth with a ruler, then tighten. Do not rotate the bit at high speed, it is unbalanced. Drilling depth control - Use the 8-piece split-ring adjustable DCT screw locking collar for drill bit to precisely control the depth of the drill. depth of a hole you want. drill; excellent for deep drilling where accurate measurement of hole depth is required; designed to hold the drill bit in place and hold the full diameter of the drill bit without the screw touching the shank. [Wide Applications] The drill depth stop set is used as a mechanical collar, perfect for precise drilling, suitable for repeated production and drilling work, suitable for drilling in wood or walls.