coombest

I will take photos as soon as I can - probably Monday...
No installation of the box is necessary - just a small box to stash somewhere uses a standard PP3 9volt (alkaline or rechargeable). Fitting to the helmet is easy enough.
It's aparently really clear but haven't used mine as an intercom, just a music player!
Radio wise - you just need a pair of radios with VOX and the appropriate Autocom connector cable to attach it to it!

HTH