Cheknao finally found it, but it’s a little expensive. . This thing seems to be very popular among foreigners, and KEN’s idol Yingwei also used it

I just found this, so I deleted the previous answer that was quite ridiculous. .

E BOW

He is often called Feedbacker by foreigners. As the name suggests, it is because he can produce sustain effects similar to feedback sounds, and due to his special principle, It makes it possible for the guitar to produce infinitely extended sounds. Almost all the master guitarists I know have this in their hands, such as Gary Moore, Vinnie Moore, etc., and some like Li Yanliang. They all use this thing for special effects in their respective works.

It is very convenient to use. When using it, just turn on the switch, put it on the strings, and then play with your left hand as needed.

Supplement! ! ! ! ! I found this later and it seems more believable. It is a kind of vibrator. The sound it pops up is very similar to a slider. The advantage is that the left hand is freed and can play more complex melodies. You can check this website/viewthread.php ?tid=623470&highlight is written by a person who uses EBOW