The General Tools and Instruments 79P Professional Automatic Center Punch 79 Replacement Point replaces a damaged or worn point on the 79 P. The 79 is an automatic center punch that punches, marks, scribes, and starts drill, nail or screw holes. The spring tensioner adjusts depending on how hard and deep you need the mark to be. The tool is made of an all steel body, the points are hardened steel. Replacing the worn out point is easy, as both the original and replacement are threaded.