Features 1、Key parts of drill chuck made with special quenching treatment to improve durability 2、Automatically tighten keyless device can automatically increase the clamping force, very practical 3、This self tightening drill chuck have high strength, good rigidity, waterproof, rustproof, and durable 4、Made of good‑quality high speed steel material, come with better hardness and hot hardness 5、The hardness is 52HB, clamping range from 1‑16mm, and the applicable machine tool is a drilling machine Specification Item Type: Self Tightening Drill Chuck Material: High speed steel Hardness: 52HB Accuracy: 0.01mm Clamping Range: Approx. 1 ~ 16mm / 0.04 ~ 0.63in Applicable Machine Tool: Drilling machine Package List 1 x Self Tightening Drill Chuck