The variation in stiffness may provide {HEAD ~ stiffer projections} at {TAIL ~ the gap} in the split ring, i.e. towards the ends of the strip of material that are curved towards each other to form the ring 
The variation in stiffness may provide { HEAD ~ stiffer projections } at { TAIL ~ the gap } in the split ring , i.e. towards the ends of the strip of material that are curved towards each other to form the ring
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH