{TAIL ~ A first monoblock element} is formed of {HEAD ~ a preferably circular horizontal rubbing plate} including a cone frustrum at its center 
{ TAIL ~ A first monoblock element } is formed of { HEAD ~ a preferably circular horizontal rubbing plate } including a cone frustrum at its center
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH