Does this clip have a gasket? Those are used for food storage over here, refrigerated or dry things in the jars that don't need refrigerating, but I can't imagine canning in them. How do you do it? I guess the whole thing boils? I found a photo (at Amazon).

This is standard in the U.S., not the size (that's a half-pint jar), but the Kerr/Ball/Mason jar type (they're interchangeable) that use two-piece lids consist of rings and the flat lids have a rubber gasket. This is used only once, and they come in boxes of a dozen for about $1.

SRS