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