I bought my home from an owner who owned a HVAC/plumbing contracting company so all mechanical systems in my home are top shelf. Our master has a Sloan flushmate system (
Flushmate). When you look into the tank it has what appears to be a CIS airbox in there complete with pop off valve
. And probably a WUR and what ever other black magic makes the system work.
I will say this...it is efficient. I'm afraid to sit on the crapper and flush lest I never be heard from again. We're careful to keep small pets 25 meters away when we hit the go button. Sounds like a jet after burner being ignited when you flush.