Rollerball with Ultra-Smooth tip for the best writing experience. Line width approx. 0.6 mm. Wallet with 4 pieces: black, red, blue, green. Waterproof according to ink standard ISO 14145-2. The innovative Super-Flow-System guarantees consistent ink flow from start to finish. The large ink reservoir has a level indicator and every drop of ink is used. The cap-off ink does not run dry even if the cap is removed for 2-3 days. The One Business has a sturdy metal clip and an ergonomically rubberised grip zone that provides a secure hold for relaxed writing.