1、INCLUDED TOOLS: Includes 3 jaw self tightening chuck, straight lines connecting rod and hex wrench, compatible with most rotating tools. 2、CLAMPING RANGE: The drill chuck can hold tools with a shank diameter of 0.3‑3.4mm, such as drill bits, for drilling, polishing and grinding. 3、SELF TIGHTENING: The collet is self tightening design, which is convenient and practical by loosening the collet with an open ended wrench. 4、BRASS ROD: The straight line connecting rod is made of brass, corrosion and oxidation resistant, and the thread is not easy to wear. 5、STANDARD SIZE: These tools have standard sizes, easy to install and disassemble, widely used in micro electric drills, electric mills, etc.