As a computer professional, I find myself constantly transferring large quantities of data, so the need for speed is a big factor for me. Firewire 400 & 800 are long gone, replaced by Thunderbolt and USB.

Thunderbolt Speed. … Thunderbolt 2 has a maximum speed of 10 Gb/s to 20 Gb/s throughput, compared to 800 Mb/s for Firewire 800, and 5 Gb/s for USB 3.0. And, unlike USBThunderbolt devices transfer isochronously (in a steady stream), making it ideal for audio and video production

Of course, thunderbolt has evolved and version 3 has theoretical throughput of Up to 40-Gbps data transfer.
Thunderbolt 1 and 2 use the same connector as Mini DisplayPort (MDP), whereas Thunderbolt 3 uses USB Type-C

Transferring data at speeds of up to 40 Gbps, which is two times faster than Thunderbolt 2 and eight times faster than USB 3, Thunderbolt 3 delivers the fastest connection to any dock, display, or device. You can also daisy-chain up to six Thunderbolt devices through a single port without needing a hub or a switch. So connecting a storage device to your computer, and then a display to your storage device, works as it’s meant to — with powerful throughput


SATA cable Certified Apple Computer Services

With Thunderbolt 3, a single USB-C port can deliver power in both directions. So a port can charge a device or, alternatively, be charged by one. And it’s capable of delivering up to 100 watts of power, so a single cable can be used to connect to a dock or display and charge your MacBook Pro simultaneously.

Drive docks for 2.5″ drives (laptop size) are much cheaper, but I also need one that fits a 3.5″ drive.
Drive docks that fit both size drives are in the $200+ price range, and that’s for Thunderbolt 1 or 2, I could purchase a Lacie Thunderbolt 3 hard drive enclosure and pull it apart to take my drives, but these are Expensive ($600+).

So, how to use an existing 2.5″ Thunderbolt enclosure to take a 3.5″ drive?
Frankendock…. So I decided to use my existing Thunderbolt enclosure (for smaller 2.5″ drives), and use an older drive sled for powering the bigger drive with an additional male to female SATA cable ($5). A thunderbolt cable link the dock to the computer. See photo of setup.
OWC Thunderbolt 2 Drive Dock