Nilfisk and Tellus plastic bayonet rubber muff curved seating ring for the connection of the hose that fits Into the base of the and the  and the vacuum cleaners, along with the other "squared off" plastic ring Pn.  and the black rubber muff Pn.  and the grey plastic bayonet Pn. and black square gasket Pn. 81542000

These are the old, singly available Nilfisk commercial hose parts that are now packaged in the kit Pn.  however, we still have some of these parts.

This "curved" ring is at 6 O'clock position in the photograph.