Parking sensors

[S4cabriolet]

I have a 2004 V6 Quattro Sport. The rear sensors have a fault (continuous beep).
I’ve seen sensors on eBay etc which are circular in shape, but on my car they are straight at the top and bottom.
Are the sensors interchangeable between models? Anyone know the part numbers I should be looking for?
TIA

My car

Widely available

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