Needle pen is marked with NP, BR, etc. In addition to the basic size, NP is an elastic head with a thickness of 0.4mm-0.8mm, and BR needle pen is an imitation calligraphy pen, which is a soft-headed needle pen with great line changes.
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Needle pens are divided into disposable needle pens and permanent needle pens. Disposable needle pen doesn't mean to throw it away once, but it can't be replaced when the ink in the needle pen is used up. However, permanent needle-tube pens can be refilled and used permanently, not only for refill kit, but also for changing the nib. The price of permanent stylus pen is higher than that of disposable pen, and the ink should be matched.
After the needle pen ink is used up, unscrew the pen body, clean and squeeze out the air in the tube, and then change the ink. Be careful not to change too much ink. Moreover, after the needle pen is used, it is easier to save ink, otherwise it will cause the pen head to be blocked. The needle-tube pen must be cleaned regularly to keep the pen tip smooth, which can also better extend the life of the needle-tube pen.