Opposite experience here, I've never seen a siphon design in the US (single or dual flush). I would have thought approximately all our toilets (outside of high-

Opposite experience here, I've never seen a siphon design in the US (single or dual flush). I would have thought approximately all our toilets (outside of high-pressure toilets in non-residential settings) had a rubber flap at the bottom of the cistern or the same hole with a dual-flush mechanism.