Slight used Genuine Apple VESA Mount Adapter for select iMacs and Apple displays by Apple, still in good shape *but all the screws are lost*
This VESA Mount Adapter Kit allows your 24-inch or 27-inch iMac computer, 24-inch or 27-inch LED Cinema Display, or Apple Thunderbolt Display to be used with a variety of alternative mounting solutions, such as wall mounts and zero-footprint articulating arms, based on the VESA flat-panel mounting interface (FPMI).
With a tool in this kit, you can remove the iMac or display stand and attach the VESA Mount Adapter. Then connect any VESA-compliant mounting solution with a 100mm x 100mm attachment.
With the VESA Mount Adapter attached, your computer or display complies with the VESA MIS-D, 100, C version specification.
Compatibility
Works with the following models:
24-inch iMac (aluminum and glass)
27-inch iMac (late 2009, mid 2010, and mid 2011)
24-inch LED Cinema Display
27-inch LED Cinema Display
27-inch Apple Thunderbolt Display