resistance of greater than about 500 n m and more preferably about 700 n m according to exemplary embodiments such foam substrate material will preferably have a 25 compression force deflection of at least 2 8 kn square meter and more preferably about 3 4 kn square meter or greater and a 50 compression force deflection of at least 2 8 kn square meter and more preferably about 3 8 kn square meter or greater such foam substrate material will preferably have at least 70 tensile strength retention after 3 hours of steam autoclave at 150 degrees celsius in this regard evaluation of foam properties may be carried out according to astm test method d3574 entitled u201c standard methods of testing flexible cellular materials u2014 slab bonded and molded urethane foam u201d the contents of which are hereby incorporated by reference in their entirety of course foam materials of different character may also be used if desired likewise while only a single layer of foam substrate material 30 is illustrated it is also contemplated that multiple layers may be used if desired the stitch forming position is defined by a row of reciprocating needles 34 extending in adjacent relation to one another across the width of the foam substrate material 30 substantially transverse to the direction of movement of the foam substrate material 30 as will be appreciated while only a single needle has been illustrated in actual practice a large number of such needles are arranged in close relation to one another in the cross machine direction between.