Nilfisk-Alto Attix 360 and Nilfisk IVB 3M vacuum cleaner filter holder. This part holds the filter in position and has the float shut off inside for the Nilfisk-Alto Attix 3 and the Nilfisk-Alto Attix 550, 750 etc as well as the Nilfisk IVB3 M.
It spins on by hand, no spanner needed.
There are also other models and brands that it will fit, including WAP and the Festo, Hilti, Makita and Stihl branded vacuum cleaners.
It used to be part number 302000472 However, for a cheaper alternative use Pn. 302000662
At the moment, standard postage is capped at a maximum of $20 within Australia.