(still using my older camera, sorry for the crappy pictures)
This is an amplified microphone-mask with volume and gain controls. I use it while drumming in a noise trio called Dos Honchos.
It contains 7 identical headphone speakers, two pots, a switch, an output jack, an IC and a battery clip; surprisingly without being cumbersome.
Screaming my face off while drumming has never been easier.