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