How many pleats are there in all beer caps? Why?
This standard not only defines the diameter of the bottleneck, but also the shape of the edge of the bottle cap and the manufacturing material.
21These lids are made in accordance with the internationally accepted German standard DIN6099, to make sure all the lids are the same.
One of the requirements of the cap is tightness, which means more pleats; at the same time, the cap is firm, which means that the amount of pleats can not be too much to ensure that each pleat has a larger surface area. 21 teeth are the best compromise between these two requirements.
