The rail section has a profile that provides {TAIL ~ one or more roller contact areas} extending a length of {HEAD ~ the rail section} 
The rail section has a profile that provides { TAIL ~ one or more roller contact areas } extending a length of { HEAD ~ the rail section }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD