Top surface 14 and bottom surface 16 are flat to {HEAD ~ about 0.001″ accuracy} so as not to degrade a spirit levels leveling {TAIL ~ accuracy} 
Top surface 14 and bottom surface 16 are flat to { HEAD ~ about 0.001″ accuracy } so as not to degrade a spirit levels leveling { TAIL ~ accuracy }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL