NilfiskCFM 175 litre 560mm container diameter ring for ease of emptying by forklift. It's just the lower part that goes around the container, not the actual bracket that's suspended from the tines.
As freight is FREE!! on this item, maximise the savings and buy some of the other related parts below, such as dustbags the filters a new hose or a new floor tool or other nozzles and accessory for you vacuum cleaner.