If you are wearing an article of clothes that has a zipper, take a minute to look at it and see if the initials YKK are on it.
90% of zippers have YKK on them.
In 1934, Tadao Yoshida started a zipper company called Yoshida Kogyo Kabushikikaisha.
These zipper facilities are all over the world now.
Their largest factory in Georgia makes over 7 million zippers per day.
I never noticed there were letters on zippers before.