Powertec 7-Piece Imperial Metric Drill Bit Stop Collar Sets With Allen, 12Mm Includes 14 total drill bit stop collars: 7 pieces with imperial size markings from 1/8" to 1/2" plus 7 pieces with metric size markings from 3mm to 12mm to accommodate all your drilling applications. Split ring design allows you to accurately control drill hole depth, eliminating over and under drilling for uniform, precision holes. Heavy duty steel construction ensures durability and tight, non-marring grip around drill bits. Easy to read size markings on each collar for quick bit identification and smooth workflow. Comes with an Allen wrench to easily install, adjust, and remove drill stop collars.