{HEAD ~ Lugs} and relief areas formed on {TAIL ~ one face} are staggered with respect to the lugs and relief areas formed on the other face 
formed on
{ HEAD ~ Lugs } and relief areas formed on { TAIL ~ one face } are staggered with respect to the lugs and relief areas formed on the other face
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH