The first sidewall and the protective wall cooperate to define {HEAD ~ a clevis structure} including {TAIL ~ a channel} 
The first sidewall and the protective wall cooperate to define { HEAD ~ a clevis structure } including { TAIL ~ a channel }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL