About This Clamping Range -You will get 5 pieces keyless drill chucks, there are 3 pieces 1/4 inches, one clamping range is 0.3 - 6.5 mm, one is 0.3 - 3.6 mm, the other is 0.6-8mm ; There is a 1/8 inch and the clamping range is 0.3 - 3.4 mm. There is a 1/16 inch, clamping range is 0.3 - 3.4mm.The drill chuck extension is small size and light weight, which will not bring extra burden to your operation Function - These keyless drill chucks can easily turn a cordless electric screwdriver into a drill or grinder; You need to turn the tail to make adjustments to quickly switch tasks and maintain work progress; They are essential power tool accessories Quick Install - This drill chuck for impact driver goes from driving to drilling in seconds to keep up with the pace of your job by a simple plug, and also give you the freedom to drill with one hand, which is great for working in tight spaces Wide Range of Applications - These drill chucks have various specifications and can be adapted to most drills and cordless power screwdrivers; They can be applied in car, garages, warehouses, offices, homes, etc Note - If you plan to drill through hard metal such as steel and if especially thick, then please use a wrench or a plier to tighten the drill bit into place for secure and accurate drilling Overview Brand : Hakkin Material : Carbide Item Diameter : 7.62 Millimeters Compatible Devices : Drilling Machine Thread Size : around 1/4 inch (6.35 mm)