One side of that material is V shaped to extend into and conform to {HEAD ~ the V shape} of {TAIL ~ said race} sufficiently along the length of the race for centering one plate 
One side of that material is V shaped to extend into and conform to { HEAD ~ the V shape } of { TAIL ~ said race } sufficiently along the length of the race for centering one plate
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH