Just in case someone knows the answer offhand, I'd like to save an afternoon of trial fittings at a supply house...
I want to connect two 4" plastic fittings (without using a short piece of hose and two hose clamps). In this case, I'm connecting a wye to a 4-3" reducer.
Is there commonly available pipe size that can couple these (4" I.D.)? If there's something close but slightly loose, I'll fill it with caulk.