{HEAD ~ This foam layer} is co extensive with {TAIL ~ the exterior surface} of this sheet, and is usually attached with an adhesive which joins the foam and the surface so no air space exists therebetween 
{ HEAD ~ This foam layer } is co extensive with { TAIL ~ the exterior surface } of this sheet , and is usually attached with an adhesive which joins the foam and the surface so no air space exists therebetween
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH 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 OTH