【Premium Ink】Premium ink glides freely across the paper, producing clear, precise lines with every stroke and a smooth, consistent writing experience 【Settle Trouble】Solve the trouble of buying ink frequently. You only need to buy it once, and you can go a long time without worrying about running out of ink 【Big Capacity】Refillable ink cartridges are designed with a large capacity, so a single replacement can be used for a long time 【Affordable Solution】The 50 Ink refills allow you to write seamlessly without worrying about running out of ink 【International Standard】The ink cartridge is 3.4 mm in diameter and is compatible with a wide range of fountain pens, so your fountain pen collection will never get dusty again