Featuring a unique auto tightening mechanism for tool release operations, it securely grips shanks from 0.3mm to 3.4mm, including common 2.35mm and 3.17mm sizes, while offering multi apertures option ( 2mm 6mm) for crosses device compatibility with various tiny motors and rotary tools Ideal for model makers, jewelers, engravers, and hobbyists requiring high accuracy machining, this drill chucks serves users who demand efficient tiny tool accessories for intricate craftsmanship Perfect for stable drilling, grinding, and polishing operations in jewelry making, PCB repair, miniature modeling, and delicate engraving projects where accuracy machining is critical This auto tightening drill chucks is engineered specifically for tiny motors under 5A, precise rotation for tiny creation tasks, making it an essential upgrade for accuracy tool enthusiasts and tiny motor accessories seekers Constructed with a portable aluminum alloy body reducing vibrations and brass mouths ensuring superior wear resistance and concentricity, this sturdy drill chucks ensures stable during extended accuracy machining projects, Manufacturer: JDNH