This is the product pictured in the foreground of the picture. It's the quick release cloverleaf part, which is fixed on to the drive on the rotor of the floor polisher and floor scrubber.
They are commonly used with Polivac branded polishers, such as the Polivac PV25 and floor sanders and scrubbing machines.
This part holds the part at the rear of the picture, the short trim pad holder with the short green bristles on it but it's not a brush, it's for holding polishing and scrubbing abrasive pads ie, the red, white, green, black one most cleaners are familiar with.
It enables the pad holder or brush to be very quickly and easily removed. No kicking to release or parts becoming seized together.
At the moment, standard postage within Australia is capped at a maximum of $20! Maximise the saving on postage and buy several Puregiene toilet rolls a box of Tissues and some soap or maybe some packets of dustbags, or a hose or a new floor tool, or some other accessories!