The Pilot FriXion Point Knock 0.4mm erasable gel ink rollerball pen uses thermo-sensitive gel ink which becomes invisible after friction created by the magic eraser at the back of the pen. The pen features a 0.4mm tip which is ideal for precise drafting and writing. The pen also equipped with a pocket clip. Please note the ink will also disappear when exposed to heat but reappear when the temperature drops below -10°C. The pen has a sleek and stylish outlook and available in various vivid colours.