YKK makes zippers. Lots of them. More than 7 Billion per year! YKK stands for Yoshida Kogyo Kabushikikaisha, which means Yoshida Company Limited. The company makes about half the zippers in the world. The zippers display the YKK trademark. Of course, it’s not large, but it’s everywhere. And that means that YKK is everywhere, any many many garments. Few brands dominate their markets as much as YKK.
YKK – USPTO trademark registration number 865610 issued in 1969 for zippers.