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