150 defined by the thickness of the expandable layer 105 at the locations of the grooves channels 110 the primary thickness 150 is determined for the intended application and for example may be 5 mm or 3 3 mm in certain applications in one embodiment the secondary thickness 150 is approximately one half of the primary thickness 140 the expandable layer 105 and the adhesive layer 130 may be manufactured by extruding the expandable layer may be formed from various expandable materials known to be useful for baffle and sealing applications one example of a suitable expandable material is a heat activated foam such as the heat activated foam sold by sika corporation of madison heights mich under the name sikabaffle u00ae and described in the following u s patents all of which are incorporated herein by reference u s pat nos 5 266 133 5 373 027 6 150 428 6 368 438 and 6 387 470 other expandable materials may also be used the adhesive layer 130 may comprise any known adhesive suitable for securing a baffle in place prior to activation the grooves channels 110 in fig3 and 4 permit activating heat applied to the baffle 100 to more quickly and effectively penetrate into the interior portion 107 of the expandable layer 105 which results in more effective and efficient expansion further the inclusion of the grooves channels 110 u2014 or any other types of voids in the expandable layer 105 u2014 results in less.