⑴ Monochrome ballpoint pen: This is the most common ballpoint pen, often in blue, black, red, etc.
⑵ Two-color ballpoint pen: generally red and blue two-color.
⑶ Three-color ballpoint pen: red, blue, and black.
⑷ Four-color ballpoint pen: red, blue, black, and green. In addition to these four, there are six-color, eight-color, and even twelve-color ballpoint pens.
According to structure
⑴ Disposable ballpoint pen, the penholder is the refill, neither can add ink nor change the refill. If the ink is used up, it can only be discarded.
⑵ A ballpoint pen that can change the refill, with functions such as buttons, springs, locking, and restoring.
⑶ The pen barrel can be rotated to extend or retract the pen core.
⑷ There are new ballpoint pens such as a combination of ballpoint pen and fountain pen, a combination of ballpoint pen and pencil, a combination of ballpoint pen and electric tester, and a combination of ballpoint pen and tiny light bulb.