a portable measurement device configured to be placed in {HEAD ~ the pathway} of {TAIL ~ the movable barrier} and have contact with the movable barrier when the barrier is moved, the portable measurement device including an interface and measuring circuit 
of
a portable measurement device configured to be placed in { HEAD ~ the pathway } of { TAIL ~ the movable barrier } and have contact with the movable barrier when the barrier is moved , the portable measurement device including an interface and measuring circuit
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH