A guide 1, wherein said housing unfolds to facilitate installation onto said track at any point along {HEAD ~ the length} of {TAIL ~ said track} 
A guide 1 , wherein said housing unfolds to facilitate installation onto said track at any point along { HEAD ~ the length } of { TAIL ~ said track }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL