Strength Technology, Stein Construction Frame supports core from inside So it is hard to break! Stein has a reinforced silica frame inside the wick. This frame is constructed to support the entire core from the inside to the core for maximum strength. This is a brand new sharp lead with a smooth writing experience and incorporates strength technology. Twist the lid to remove the core. Mechanical pencil refill; Lead diameter: 0.04 inches (0.9 mm); Hardness: HB; Lead length: 2.4 inches (60 mm); Number of leads: 36 pieces; Quantity: 1