Silent Plus ST7 for Trumpet

Silent Plus System
For trumpet.
It's about 30 years old, but it works.
I haven't tested if it works with batteries, so I don't know, but it worked fine with the adapter.
I cannot be responsible for the tone quality, etc.
How about this for someone who is just starting the trumpet and wants to practice at home!
If you need earphones, I will disinfect them and include them. Please write this in the comments when purchasing.