This is an Ikea Linnamon headphone holder. It's a very basic holder that comes with a screw for use on smaller tables. The widest opening is 34mm, which is the size of the Linnamon table top. The screw must be able to clamp something that is 2cm or thicker. If there are enough requests, I will try to make a longer screw. This headphone holder is perfect for organizing and switching between different headphones.