{HEAD ~ The retention channel} extends substantially an entire length along each edge of {TAIL ~ each part} receiving area 
{ HEAD ~ The retention channel } extends substantially an entire length along each edge of { TAIL ~ each part } receiving area
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH