[Ultra-low friction jet stream ink mounted!] The world's first breakthrough ink, has achieved a smooth writing feeling to become a habit with a low writing resistance. Since also speedy is drying of the ink, the hand is stained stress also reduced. Backflow of ink also prevents the twin ball mechanism, has a built-in spring chip to prevent the leakage of ink from the pen tip. Knock-type / oil-based ballpoint pen Ball diameter: 0.7mm ink color: black, red, blue, green Size: shaft diameter diameter 12.9mm × thickness 17.7mm × total length 145.1mm