One Handed Operation ]: 5.1" Length/ 0.78" Diameter Automatic Center Punch, One Handed Operation, simply adjust to desired spring tension, press firmly against work piece for automatic centre punch. [ Advanced Material ]: Needle: High Speed Steel(HSS)/ Shell: No.45 Steel. Hardness up to HRC58~65. Features adjustable spring loaded design for variable impact strength and hardened tip for long service life. [ Feature ]: Makes accurate marks without the need for a hammer before punching to prevent the drill bit from running off; also be used for emergency escape, crushing broken windows. [ Widely Application]:Break glass and iron plate/PVC plastic / Steel plate/ wood/ wall positioning, can accommodate various types of materials such as wood, plastic, metal, glass, leather.