Nilfisk-ALTO and Gerni Neptune 4 hot water high pressure washer exhaust limit switch.
I'm not sure, but I think these sense the temperature of the exhaust.
Maximise the saving on postage and buy several Puregiene toilet rolls a box of Tissues and some soap or maybe some packets of dustbags, or a hose or a new floor tool, or some other accessories!
At the moment, standard postage within Australia is capped at a maximum of $20!