which are in the form of radial spokes extending from the outer surface of wall 12 to the inner surface of wall 16 provide connecting means between the two walls outer wall 16 has a slot 20 therein slot 20 extends at an acute angle from the surface of wall 16 and has a generally rectangular shape of course the spool may take any of a variety of conventional shapes and still be suitable for use in the inventive device fig3 depicts a film 22 which is a conductive film fig2 depicts a cross section of a metallic or conductive strip which is in the form of a v having arms 24 fig3 depicts a conductive film 22 having crimped on the edge thereof a strip such as that depicted in fig2 the 34 u 34 or 34 v 34 shaped strip is made from a conductive metal typically this can be brass although other metals can be used in one instance brass shim stock having a thickness of 0 010 inches was used the leading edge of the film is inserted into the slot formed by the v of the strip and the strip is then crimped thereon using high pressure e g about 3 000 lbs generally the strip has a length approximately the same as or less than the width of the film as a result of this high pressure the brass strip penetrates through the film and assures contact with the conductive layer of the film to provide crimped end 26 it is this crimped end which is.