The modern interlocking zipper was perfected in 1914 by Swedish-born Gideon Sundback. “Sundbäck developed a version based on interlocking teeth, the “Hookless No. 2″, which was the modern metal zipper in all its essentials. In this fastener each tooth is punched to have a dimple on its bottom and a nib or conical projection on its top. The nib atop one tooth engages in the matching dimple in the bottom of the tooth that follows it on the other side as the two strips of teeth are brought together through the two Y channels of the slider.”
The modern Zipper Cup was perfected sometime in the late aughts by MEGAWING. “The intricate design mechanism of a zipper reflects the bonding and friendship of two people, which is why they are sold in pairs. Great for gifts to newly weds, friends, parents, anniversary etc.” Hope it comes with XXY teabags.