StarTech.com Thunderbolt 3 to FireWire Adapter - External PCI Enclosure - PCIe Card plus TB3 Chassis - The Thunderbolt 3 to 1394 FireWire adapter connects your FireWire peripherals to your Thunderbolt 3
Amazon.com: HP 3UU05AA Dual Port Add-in-Card - Thunderbolt Adapter - PCIe - Thunderbolt 3 X 2 : Electronics
Node Duo - Thunderbolt 3 PCIe expansion chassis for 2 cards | AKiTiO