In preferred embodiments, {HEAD ~ the pitch} between {TAIL ~ corrugations} may be five inches, with a depth of one half inch 
between
In preferred embodiments , { HEAD ~ the pitch } between { TAIL ~ corrugations } may be five inches , with a depth of one half inch
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH