The RS 6661A can add any PCIe x4, x8 or x16 card to a Thunderbolt™ 3 capable computing platform such as media capture, Ethernet, Fibre Channel, or external Storage/RAID controller cards.
 
RS6661A key features:
Thunderbolt™ 3 40Gb/s Ports / Daisy Chain support for up to 6 devices
Dual Ultra-Quiet, High-Efficiency Cooling Fans
Easily install nearly any full-height/full-length PCIe 3.0 card
(Storage I/O, Networking, Video, Sound)
Versatile Storage & Connectivity Expansion; NVMe RAID Drives, USB/eSATA/Mini-SAS connectivity