Blackmagic Design external GPU, AMD Radeon RX 580 8GB GDDR5, Thunderbolt 3. This is the unit Apple sold as the official external graphics option for Intel Macs. Nearly silent, the entire aluminum enclosure is the heatsink.
Doubles as a Thunderbolt dock: HDMI out, USB-A ports, and 85W charging passthrough, so one cable powers and drives a MacBook.
Important compatibility note, and I would rather tell you now than deal with a return: this works with Intel Macs that have Thunderbolt 3. It does NOT work with Apple Silicon Macs (M1 through M4), Apple removed eGPU support. It also works on Thunderbolt-equipped Windows and Linux PCs.
Tested working before listing: connected to a 2018 Mac mini, the RX 580 shows up in System Information next to the built-in graphics. Not sold as untested. Includes the power cable.
That 2018 Mac mini (6-core i5, 32GB RAM, 512GB SSD) is in my other listings. Apple sold these two as companions, and the eGPU is exactly what fixes the Mini's integrated graphics. Check my other items.