StarTech.com Thunderbolt 3 to Thunderbolt 2 Adapter, TB3 Laptop to TB2 Displays & Devices, Thunderbolt 2 20Gbps or Thunderbolt 1 10Gbps, TB3 to TB2 Converter, TB3 Certified, Windows & Mac - 8in Attached Cable (TBT3TBTADAP) - Thunderbolt adapter - Mini Dis

Use first-generation Thunderbolt and Thunderbolt 2 devices with your new Thunderbolt 3 computer.
With this adapter, you can connect Windows and Mac based Thunderbolt 3 computers to older Thunderbolt devices, such as external hard drives, Thunderbolt displays, and older Thunderbolt capable Mac computers.
Because this adapter is backward compatible, you can connect to first-generation Thunderbolt devices at 10Gbps speed. With Thunderbolt 2 devices, you can connect at 20Gbps. The adapter satisfies all requirements for bi-directional data transfers and simultaneous power for bus-powered devices.
Your computer's Thunderbolt 3 ports might not function properly until you update one or more of the following on your computer: BIOS, Thunderbolt firmware, Thunderbolt 3 controller drivers, Thunderbolt 3 software.
The required updates will vary depending on your computer.