Rollerball Can Be Refilled With The Exchangeable One Change Cartridge With Ultra-Smooth Tip For The Best Writing Experience. Line Width Approx. 0.6 Mm, Writing Colour Black, Waterproof According To Ink Standard Iso 14145-2. The Innovative Super-Flow-System Guarantees Consistent Ink Flow From Start To Finish. The Cap-Off Ink Does Not Run Dry Even If The Cap Is Removed For 2-3 Days And, Besides This, Is Quick-Drying And Smudge Proof. The One Change Has A Sturdy Metal Clip And A Rubberised Grip Zone That Provides A Secure Hold For Relaxed Writing.