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Nice... So are the holes flat or punched with a lip? looks like both. Folded seam is a nice touch.



The reason it looks like both is that what you are seeing is an excellent example of the "burr" that developed when the punch die started to dull. The tooling was then switched from a flat hole punch to a Dimpled punch to raise this "burr" away from the media and avoid the possibility of the burr side (if the band was assembled with the burr side towards the filter media) coming into contact and chafing the filter media. The Dimpled holes then created an unmistakable marking of which side of the band was the outside during the assembly process.

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