These have a low level plinth, almost at the floor level of the bathroom. They enable the disabled to step across into the shower rather than step up. They usually result in a drain lower than the external outlet, hence the need for an electric pump (mine is a Whale). Servicing would involve combined electrician and plumber skills.
I know from past postings that at least one member here (I can't recall who) has such a set-up. If he is still around, could he or anyone else advise what the servicing interval should be, and any other relevant comments please?