a sensing edge, said leading edge and said sensing {TAIL ~ edge} extending between the concave and convex {HEAD ~ edges} of one end of the material layer, 
a sensing edge , said leading edge and said sensing { TAIL ~ edge } extending between the concave and convex { HEAD ~ edges } of one end of the material layer ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH