Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter
The Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter lets you connect Thunderbolt and Thunderbolt 2 devices—external hard drives and Thunderbolt displays, for example—to any of the Thunderbolt 3 (USB-C) ports on your MacBook Pro.
As a bidirectional adapter, it can also connect new Thunderbolt 3 devices to a Mac with a Thunderbolt or Thunderbolt 2 port.
In addition, it can be used to connect Thunderbolt-enabled displays—such as the Apple Thunderbolt Display and LG Thunderbolt 2 displays—to any of the Thunderbolt 3 (USB-C) ports on your MacBook Pro. However, using this adapter with an Apple Thunderbolt Display requires a power source because
Note: This adapter does not support DisplayPort displays like the Apple LED Cinema Display, third-party DisplayPort or Mini DisplayPort