Product Introduction: [Ultra Low Friction Jet Stream Ink Refill] The world's first revolutionary ink creates a smooth writing experience with low writing resistance. Also, since the ink dries quickly, it reduces the stress of getting dirty hands. Twin ball mechanism also prevents ink backflow and includes a built-in spring tip to prevent ink leakage from reaching the nib. Note (Disclaimer) > Please be sure to read; Product specifications may change without prior notice. Please use it correctly according to the intended use.