These phone holders are custom designed to mount on top of these Airdyne displays.
I 3D printed these myself. The finish turned out well, but they are not "factory level" finish as you can see by the photos. There are some imperfections.
The actual phone holding part measures 195 wide x 125 high x 20 deep millimeters.
Description
Phone holder compatible with Schwinn Airdyne AD7/AD8/Pro/ADX exercise bikes Version 2