A band of bags of plastic material connected with each other by perforation lines. In the two end parts of each perforation line the number of perforations and/or the width of the perforations per unit of width is greater than in the central part of the perforation line. A device for manufacturing said band of bags comprises a perforating member with equidistantly spaced first perforating pins and second perforating pins are present on either side of a central area between the first perforating pins.
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