The grooves on {HEAD ~ the front end} of {TAIL ~ device} face proximally and are disposed on opposite sides of the device in alternating fashion 
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The grooves on { HEAD ~ the front end } of { TAIL ~ device } face proximally and are disposed on opposite sides of the device in alternating fashion
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH