Each of the guide rails comprises {HEAD ~ an end} proximate to {TAIL ~ the aerosol valve} and an end distal from the aerosol valve 
proximate to
Each of the guide rails comprises { HEAD ~ an end } proximate to { TAIL ~ the aerosol valve } and an end distal from the aerosol valve
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH