Preferably, the invention relates to a device wherein {HEAD ~ the device} comprises {TAIL ~ a guiding rail} and an interconnecting bar 
comprises
Preferably , the invention relates to a device wherein { HEAD ~ the device } comprises { TAIL ~ a guiding rail } and an interconnecting bar
OTH OTH 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