This is a BOSS wireless headphone-type digital amplifier. It's easy to get high-quality, stress-free instrument sounds, which greatly helped increase my motivation for practice. It has some signs of use, but it's in good condition. You can enjoy high-quality, surround-sound amplifier sounds anytime, anywhere, without stress. Since you can play the sound of a guitar, bass, keyboard, etc., and a backing track simultaneously, it was very convenient for copying songs and practicing for live performances. It's useful at home, as well as in the dressing room. Operation has been confirmed. Regarding the specifications, the Bluetooth connection method is a bit tricky, so I recommend reading the manual before use. The main unit, receiver, and one USB charging cable are included.