The clamps are a registered brand of the WECK company. They are for fastening the lid to the jar. It´s out of rustless steel. For an originally round rim jar, you always need 2 clamps.
The glass lid has the WECK strawberry relief as a logo on top. The glass lids have different available sizes of the diameters 60mm, 80mm, 100mm and 120mm. Additionally, you need a rubber ring plus 2 clamps.
Rubber rings are required for an airtight closing. They work like a sealing ring. You lay them between the glass lid and clamps. Originally ones are orange-red. Before using them, rinse them out in hot vinegar. Porous ones should be eliminated, because they don´t shut the jar properly.
WECK preserving jars are officially round rim jars. They differ from screw lid jars. A special indicator is the WECK strawberry logo on top of it. Round rim jars have a diameter of 60mm, 80mm, 100mm or 120mm. There are shapes like mold ones (conical), tulip or deco jars (bulbous), cylindrical jars, convex jars plus juice jars. Depending on the shape, they contain 2.82 fl.oz to 95.03 fl.oz.