Sorry to disagree John, but the spherical jobby is an independent and separate sand blaster. I used to own one. They came with shaped rubber heads that were stored in the holes in the base. The sphere held the grit, it was pulled out by a venturi arangement , conveyed to the blasting nozzle, and round the hose was a large diameter pipe also connected into the sphere, and at the business end the rubber heads pushed onto it. The sphere was connected to a vacuum cleaner so was at low pressure, and the grit having left the nozzle was contained within the rubber head and sucked back to the sphere. The heads were shaped to fit round the various mouldings and curves of car body work and the were inteded for spot blasting of rust damage on car panelwork.