You can adjust the volume of the microphone by unscrewing the lower part of the tube body and using the square button. The button on the right side increases the volume, while the one on the left decreases it.

Yes, you can replace the 18650 battery yourself by purchasing a replacement.

Yes, this microphone is indeed plug and play, which means that it can be used straight away without any complicated setup or additional software installations.

Yes, the microphone can be used with any wireless speaker as long as the speaker has a compatible 6.35mm interface.

No, a single receiver can only support up to two mics at a time, so you'll need an additional receiver to use all four mics. Alternatively, you can use two sets of TW320 products at the same time to enable the use of four mics simultaneously.