From Amazon
StarTech.com Thunderbolt 3 PCIe Expansion Chassis, External Enclosure With One PCI Express Slot, PCIe Box for Laptops / Desktops / All-In-Ones, 5K/4K Output Via TB3/DP, TAA Compliant (TB31PCIEX16)
Technoworld PLC
StarTech.com Thunderbolt 3 PCIe Expansion Chassis with DisplayPort - PCIe x16 TB31PCIEX16
This product is also available at 2 unverified merchants.