The Echo Express SEL - Thunderbolt 3 Edition supports one half-length (up to 6.6 inches long), low-profile, single-width PCIe card; PCIe 1.1, PCIe 2.0 and PCIe 3.0 cards are supported.
Through its x8 PCIe 3.0 slot, this little expansion system supports many low-profile PCIe cards (Thunderbolt-compatible 16Gb and 8Gb Fibre Channel, 40Gb and 10Gb Ethernet, video capture and processing, SAS and SATA host bus adapters, and RAID controllers) and connects it to your computer through a single Thunderbolt 3 cable.