wherein the pair of fifth rollers sandwiches {HEAD ~ the pair} of {TAIL ~ second bent parts} and is mounted so as to slidably contact the pair of second bent parts of the intermediate rail 
wherein the pair of fifth rollers sandwiches { HEAD ~ the pair } of { TAIL ~ second bent parts } and is mounted so as to slidably contact the pair of second bent parts of the intermediate rail
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH