In 2013, the newly developed non-dry mechanism was patented (No. 5371571) for its uniqueness.
Water-based ballpoint pen refills need to replace the air residue in the pen when the ink runs out. If the air is not replaced, a vacuum will form, causing problems such as ink blowing out. Therefore, it is necessary to have a hole (air exchange hole) to let air in.
Conventional water-based refills have a small hole in the front part for air exchange.So air comes into direct contact with the ink feeder or reservoir.If forget the cap on, the nib would dry out, and would not be able to write.
To solve this problem, OHTO have developed a unique mechanism that prevents air from direct contact to the ink feeder and reservoir. As a result, water-based ballpoint pens equipped with the OHTO C-300 are free from drying out even if the capping is forgotten.