This is an earphone-microphone type sound amplifier that allows you to clearly hear surrounding conversations and sounds. It seems to have an automatic volume adjustment function that suppresses sudden loud noises. Size: 4.6 x 9.3 x 1.4 cm Earphones are unused, and the sound amplifier itself is also unused, but operation has not been confirmed. Transactions are 3N (no returns, no refunds, no exchanges).