some instances the reinforcing may be molded in the body when it is formed thus eliminating the closure plugs 63 the upwardly and inwardly side surfaces 42 44 are shown as being formed by the surfaces 40 and 42 which extend upwardly from the outer edge of the surfaces 34 and 35 respectively and the surfaces 40 41 are joined at their upper ends by the upwardly and inwardly sloping surfaces 43 and 43 39 as illustrated in fig3 and 4 an alternate embodiment of the elongated elastomer body b is illustrated wherein like numerals refer to like parts the body b includes a base member 20 and an upper member 30 the base member 20 includes the bottom surface 21 surfaces 22 23 24 25 as previously described and the upper member 30 includes the surfaces 34 and 35 which extend outwardly from the upwardly extending surface 31 and 32 at each end of the surfaces 24 and 25 side surfaces 42 and 44 are again provided however it will be noted that in this configuration the extent of the upwardly and inwardly sloping surfaces 43 and 43 39 are of substantial extent in relation to the surfaces 40 and 41 which extend upwardly from the surfaces 34 and.