The Clamp Hub Pro is designed for the iMac and iMac Pro from 2017 to 2019, which have Thunderbolt 3 (USB-C) ports. It does not fit the Studio Display. It is not compatible with the late 2015 iMac 5K or other pre-2017 iMacs, because those use Thunderbolt 2, which is not the same as Thunderbolt 3. If your older iMac has an open USB-A port, you can use a USB-C female to USB-A male adapter to connect the Clamp Hub Pro.