To drill holes accurately, you must start with a punch mark to center the bit.
These center punches are spring loaded; pressing down on the knurled brass barrel recoils the double springs and drives the hardened punch tip into your work, providing a deep, clear registration mark.
The standard punch has a 7/8" long tip. The long-nose version has an extra-long tip for marking through thick objects, such as shelf standards or cleats (max. 1-1/8" thickness).
The self-centering model has a chamfered nosepiece to automatically center in a countersink for proper screw placement, and has a 5/8" long tip.
All have steel tips hardened to Rc45 and are force-adjustable. Sold individually or as a set of three. Overall length ranges from 5" to 6".