Smooth enough to become addictive once you use it. Easy to write on and very exciting. Traditional oil-based ink has a higher viscosity and relatively heavier writing and newly developed ink has a lower viscosity and a lighter writing experience. No ink backflow! Twin ball mechanism Prevents ink from being DC! Spring tip. Extremely quick drying. You can write dark and clear drawing lines. Oil-based ballpoint pen; Ball diameter: 0.03 inches (0.7 mm); Shaft grip color: Black; Ink color: Red; Body length: 5.5 inches (139.6 mm); Refill: SXR7; Shaft diameter: 0.4 inches (11.3 mm); Art Supplies Shop Dot Com Postcard A; Limited product!! 1 x Cute Animal Postcard