Anterique Brass Collection Ballpoint Pens are innovative, Japanese ballpoint pens that combine Mach Ball ink with vintage-inspired forms. Ballpoint pens in the past used "sticky” ink, but these oil-based ballpoint pens use "ultra-low-viscosity ink" (Mach ball ink). "Ultra-low viscosity" is ink that is extremely smooth. To prevent leaking, the special ink is combined with an ultra-precision roller ball. These pens also feature a built-in spring to precisely control the flow of ink. The lower shaft of these beautiful pens is machined from a brass bar with an overall weight of 26g.