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