In its preferred embodiment, the fabrics are of a non woven spunbonded olefin Tyvek with polyethylene or polyvinylidine chloride laminated to one side thereof as aforesaid; but the fabrics may be of any material such that like laminated sides may be ultrasonically bonded together and in which a laminated side can be ultrasonically bonded to an unlaminated side, but in which an unlaminated side cannot be ultrasonically bonded securely to an unlaminated side under conditions which permit ultrasonic bonding of {HEAD ~ other permutations} of {TAIL ~ sides} 
In its preferred embodiment , the fabrics are of a non woven spunbonded olefin Tyvek with polyethylene or polyvinylidine chloride laminated to one side thereof as aforesaid ; but the fabrics may be of any material such that like laminated sides may be ultrasonically bonded together and in which a laminated side can be ultrasonically bonded to an unlaminated side , but in which an unlaminated side can not be ultrasonically bonded securely to an unlaminated side under conditions which permit ultrasonic bonding of { HEAD ~ other permutations } of { TAIL ~ sides }
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