Features: Made of 45 steel, solid and durable to use. Good metal texture, comfortable surface, easy to clamp, so that the output torsion becomes larger. Beautiful and practical design of t he surface convex and concave, so that before and after the set can effectively cope with and can reduce the shaking jacket. Keyless design, tightening and loosening is by hand force, which offers a quicker and easier chucking and unchucking. Widely used with various drill machines, milling machines, lathes, boring lathes and electric hand tools. Specifications: Material: 45 steel Accuracy: 0.002 Chuck Capacity: 0-16mm Chuck External Diameter: 48mm / 1.81inch Chuck Length: 99mm / 3.9inch Arbor Type: M3-B18 Arbor Length: Approx. 138mm / 5.43inch Total Length: Approx. 210mm / 8.27inch Weight: Approx. 1333g Package Included: 1 x Keyless Drill Chuck 1 x M3-B18 Arbor Note: 1. Only things package included, no other stuff. 2. Please allow 1-2mm error due to manual measurement. Thanks for your understanding.