Delguard Type ER Mechanical Pencil / Zebra

It protects the lead from breaking under any angle and even under strong pressure. When strong vertical pressure is applied to the paper, a spring built into the shaft lets the lead escape upwards to prevent it from breaking. When strong diagonal pressure is applied, a metal part at the tip automatically comes out to wrap around and guard the lead. These two mechanisms automatically adjust their distribution based on the angle and strength of the applied force and work accordingly. If you start writing by clicking the mechanism more than 4 times when the lead is not protruding, it may break. The lead may break when using colored leads or leads that are 3B or darker.