of respective first and second vertical sidewalls 56 58 include respective first and second inwardly extending opposed engagement elements 64 66 which are separated by a slit a space or similar relationship 67 the end clips 44 46 are made from polymeric material such as but not limited to polyethylene polyolefins polyesters nylons polypropylenes etc and the resiliency of the resulting configuration will typically allow the end clips 44 46 to be snapped onto the closure 24 prior to the welding or similar bonding process as shown in fig3 the first and second flanges 34 36 are positioned between first and second vertical sidewalls 56 58 and engaged in slit space or similar arrangement 67 formed by first and second inwardly extending opposed engagement elements 64 66 first and second inwardly extending opposed engagement elements 64 66 pierce the first and second closure flanges 34 36 and are then welded to each other through the first and second closure flanges 34 36 by ultrasonic welding fig3 further illustrates welder 100 which can be construed as a heat welder an induction welder an ultrasonic welder or similar device to apply energy to the clips 44 46 as can be seen in fig4 7 the bottom views of the first and second inwardly extending opposed engagement elements 64 66 have various toothed or similar.