THey can be speced in new gear, or installed in the field, pretty simple to do, we sometimes install them for free for our customers that have us test thier MV gear on a regular basis because it saves us time in the future and is safer than using normal ground clamps (They will not come off)
It is simply a bolt that has a small trailer hitch on it, it replaces the normal bolt in the bus. They usually have a rubber boot over them with a hole in it so you can remove the boot with your shotgun. When you need to ground the gear you remove the boot, put your grounds on and tighten them down all using a shotgun.