{HEAD ~ Each notch} comprises a first angled sidewall and {TAIL ~ a second angled sidewall} having an included angle from horizontal 
comprises
{ HEAD ~ Each notch } comprises a first angled sidewall and { TAIL ~ a second angled sidewall } having an included angle from horizontal
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH