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 clamp sizes ranging from 2~13mm, suitable for many types of drill.5. Keyless and self-tightening design is more in accordance with human technology.Specification:Features:The chuck can hold the drill bit tightly and firmly, not easy to loosen.Durable and has long service life, suitable for long-term work.Easy to install and disassemble, more convenient and labor-saving.Wide range of clamp sizes ranging from 2~13mm, suitable for many types of drill bits.Keyless and self-tensioning design is more in accordance with human technology. Specification:Diameter: 43mm/1.69inLength: 58mm/2.28in (3-5mm tolerance)Connection size: 1/2-20UNFClamp range: 2 ~ 13 mm / 0.04 ~ 0.51 inchPackage List:1 x Drill ChuckNote:Before purchase, it is necessary to verify whether 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 thumb thread and F is fine thread).