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