about 15 pounds preferably the frangible regions are provided by strategic die cutting of the closure profile and or channel interlocking portions it will be appreciated that other methods such as selective perforation and the provision of weaker materials in frangible areas can be utilized preferably frangible areas are selected to fail when a force is applied to the sealed closure which is less than sufficient to separate the interlocked portions of the closure preferably the physical properties of the materials from which the closure is constructed are selected to be sufficiently stiff to resist prying of the interlocking portions of the closure to disengage the interlocked portions without extensive readily detectable damage to the closure portions subjected to prying or activating the tamper evidencing features of the closure materials of construction and methods are discussed in more detail below preferably materials of construction of the inventive closure are selected to resist defeat through softening of the materials to permit mechanical manipulation to open the closure without activating the tamper evident features of the closure in some embodiments the closure may comprise a conventional interlocking closure one that does not employ frangible regions with a slider which contains tamper evidencing features one example of this is slider 600 illustrated in fig6 slider 600 is preferably selected to have a length along section u201c a a u201d which exceeds that of the closure over which it is operated with reference to the cross section along section u201c a a u201d of.