Nilfisk and Tellus GS90 GM90 and Allergyvac Vacuum Cleaner Cotton Main Filter
2,000 cm2 Cotton Main Filter For Nilfisk and Tellus GM90 and GS90 and G90 Allergyvac as well as the "Mini Merc Vac" for Mercury.
It has a copper ring that clips into 3 plastic hangers at top of container.
These aren't "JUST" a cotton bag, they have a micron rating and they are part of the Nilfisk dust management system, which made these original machines, a world leader for sensitive dusts, hazardous dusts as well as nuisance dusts.
For the photo, I did use one from a customers machine, save getting a new one out of a packet.
At the moment, standard postage is capped at a maximum of $20 within Australia, so maximise the saving on postage and buy something in the related parts below!