old-fart
Maybe not the oldest, but possibly the fartiest!
The silicone cap cannot be replaced, so if you dont want it, I’ll take it! I lost mine once, then miaculously found it, but I’d love to have a spareAm I the only one who tossed that annoying rubber flap? Nothing goes down the hole that can't be blown out.
I, and I imagine many others, use the cap for odor control and to ensure nothing falls into the heater bowl that shouldn’t be there.