SPECIFICATION --- Wide range of collet sizes from 2-13mm/0.04-0.51in, suitable for many types of drill bits. Diameter: 43mm/1.69in; Length: 71mm/2.8in; Connection size: 1/2-20UNF; STRONG CLAMPING FORCE --- its unique design can easily convert the torque applied by the handle into a larger clamping force, hold the bit firmly and securely , not easy to loosen. GREAT PERFORMANCE --- Keyless and self-tightening type design is more in line with human engineering. With heat treatment, the product has good toughness and superior structural strength. EASY TO USE --- Durable and has a long service life, suitable for long time work. Easy to install and disassemble, more convenient and economical. Have good metallic texture and comfortable coating surface.