Astaire & Rodgers, Torvill & Dean, Baily's & Bailys (had to get booze in there), Birds of a feather flock together, Cistern & Pan, No1s & No 2s. They're all designed to go together.
I've just fitted a Caroma ceramic 3/4.5 system in my PPOR and have another spare ready for the ensuite reno...