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