Nilfisk and Nilfisk-ALTO floor scrubber scrubbing and polisher pad plastic retainer with stainless steel wire clip. The price is for each one. These seem to be used in about 95% of the floor scrubbers I've seen, both rider scrubbers and walk behind auto floor scrubbers
There are two parts, the part that is screwed on by 3 stainless steel screws to the padholder disc, which has the very sharp points that stick out to grip the abrasive pads. The part with the clip then pushes down into the centre of the pad and clips onto the part screwed onto the disc.
At the moment, standard postage within Australia is capped at a maximum of $20!