Cello BUTTERFLOW Ball Pen Refill- Blue (10 Pcs)Cello Butterflow Ball Pen Refill Specially designed for Cello Butterflow Ball Pens Features Lubriflow ink system for super smooth and effortless writing Long lasting refill with consistent ink flow until the last drop Quick drying, smudge resistant ink for clean and neat notes Precision tip ensures sharp, clear, and comfortable writing Easy to replace, keeping your pen performing like new Specifications: Refill Type: Ball Pen Refill Tip Size: 0. 7mm