●Diameter:43mm/1.69in; Length:58mm/2.28in; Connection Size:1/2-20UNF; Clamp Range:2 ~ 13mm / 0.04 ~ 0.51in . chuck can hold drill bit tightly and sturdy,not easy to loose. ●Large range of clamp size which range from 1~13mm,suitable for many kinds of drill bit. ●Keyless and self-tighten type design is more in accordance with human engineering. ●and has long service life,suitable for long time work. ●Easy to install and disassemble, more convenient and labor-saving.