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