Nilfisk 38mm industrial vacuum cleaner hose rubber protection rings. They're for protecting hoses from rough surfaces, for example car detailing in car yards. They slides on to the hose and then grips.
Please note: the photo shown is of the 32mm protection rings, however the 38mm rings are almost identical.
At the moment, standard postage is capped at a maximum of $25 within Australia, so maximise the saving on postage and buy something in the related parts below!