Revolutionary Sliding Sleeve Technology automatically advances lead for uninterrupted use. Click pencil top to advance tip, then shake twice to expose lead. Clear window displays unique spring mechanism. Contoured barrel provides added comfort for extended periods of time. Writes 0.5mm crisp, fine lines. Soft, latex-free grip provides added comfort and control. Refillable with Pentel Super Hi-Polymer lead and PDE-1 erasers.