No waste. The fountain pen is a commonly used writing instrument. It was invented in the early 19th century and designed by American Waterman. Among them, professionals said that as of July 20, 2022, all fountain pens use ink sacs. However, the internal air pressure of the ink sacs can control the amount, which is not wasteful and is easy to replace. Ink sacs are also called ink bladders, ink bladders, etc., and are mainly used Replaces the ink cartridge of the matching fountain pen.