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