A device supports the assembly from a support and {HEAD ~ a safety device} loosely extends from a first channel to {TAIL ~ the second channel} 
loosely extends to
A device supports the assembly from a support and { HEAD ~ a safety device } loosely extends from a first channel to { TAIL ~ the second channel }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL