1. The chuck can hold the drill bit tightly and firmly, not easy to loosen. 2. Durable and has a long service life, suitable for long-term work. 3. Easy to install and disassemble, more convenient and labor-saving. 4. Wide range of clamping sizes from 2~13mm, suitable for many types of drills. 5. Keyless and self-tightening design is more in line with human engineering. Specification: Features: The chuck can hold the drill bit tightly and firmly, not easy to loosen. Durable and has a long service life, suitable for long-term work. Easy to install and disassemble, more convenient and labor-saving. Wide range of clamping sizes from 2~13mm, suitable for many types of drills. Keyless and self-tightening design is more in line with human engineering. Specification: Diameter: 43mm/1.69in Length: 58mm/2.28in (3-5mm tolerance) Connection size: 1/2-20UNFClamp range: 2 ~ 13 mm / 0.04 ~ 0.51 inches Package list: 1 x Drill Chuck Note: Before purchasing, it is necessary to verify if the connection thread of your electric drill is 1/2-20UNF. (1/2 - 20 is the definition of thread specification. Specification: 1/2; number of threads (T): 20. UNF, UN is the standard code for inch thread and F is fine thread).