Ink bag, also known as ink bladder, ink bladder, etc., is mainly used to replace the ink core of supporting pens.

Ink bag is a tube containing ink. It can be directly inserted into the pen and covered. It is disposable. Generally, it contains a small bead to prevent ink splashing. Although it works well, the cost performance is not particularly high. When the ink in the ink bag is used up, it is discarded. In addition, similar products also have ink absorbers, which can absorb ink and be used repeatedly like ordinary pens.