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