It's nothing like mine. Do you mean the sink/shower inlet to the thing, which
will be the two lower wotsits, or the connection to the outside world, which
probably comes off the top. On mine, the latter is a silicone rubber tube
clamped with a jubilee clip to a plastic fitting which connects to solvent
weld.

Tip: don't use push-fit for the "exhaust". Otherwise, Saniflow are somewhat
maligned IMHO