Descriptions:. Automatic spring loads then releases at top of cycle with force to create center punch.. Spring pressure can be adjusted by simply rotating the knurled top of the punch.Specifications:Material: steelSize: about 13cmColor: black . Hand-automatic centre punch.. Simple and accurate to use knurled handle prevents slipping.. No hammer required - just push down with hand and spring action strikes the punch head.. Gives a precise starting point on steel and other materials.. Can also be used for breaking glass in an emergency.