A windup/unwind mechanism can be connected to the roll and is capable of locking in {HEAD ~ selected positions} for selecting {TAIL ~ the tension} of the barrier member 
for selecting
A windup / unwind mechanism can be connected to the roll and is capable of locking in { HEAD ~ selected positions } for selecting { TAIL ~ the tension } of the barrier member
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH