Stalogy 015 Low-Viscosity Oil-Based Ink Ball Point Pen 0.7 MMSmooth Writing This refillable ballpoint pen writes exceptionally smoothly thanks to its low viscosity ink. Perfect for writing a mix of line weights and styles used in handwriting. Nitoms Stalogy S5110 Low viscosity oil based ink is extra smooth 0. 7 mm line width Black Ink Order refills here A Japanese company in business since 2012, Stalogy aims to elevate the "standard" level of stationery. Their motto is, "What should have been, is."