Specifications: Vivid and smooth writing. Product Size: Maximum Diameter 0.1 x Total Length 3.8 inches (3.5 x 96.0 mm); Product Weight: 0.03 oz (0.8 g); Ball Diameter: 0.02 inches (0.5 mm); Ink: Water based pigments; Compatible products: Gel, Sharbo, Gel Sle, Sarasa 2+S, Sarasa 3