Use of three rails makes {HEAD ~ a total length} of {TAIL ~ the slide rail} shorter to provide a compact slide rail 
of
Use of three rails makes { HEAD ~ a total length } of { TAIL ~ the slide rail } shorter to provide a compact slide rail
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH