Why is the brightness of the neon tube of the test pen on the market generally not high?
You all know that it is a neon tube. For the cost issue, you can buy some high-end ones with LCD, and the display will be much better.

Why is the brightness of the neon tube of the test pen on the market generally not high?
You all know that it is a neon tube. For the cost issue, you can buy some high-end ones with LCD, and the display will be much better.
