1. Best Solution: Connect two 2.5 inch U.2 (SFF‑8639) PCIe NVMe SSDs to PCIe x8 slots in the system via SFF‑8643 cables (not included). Allows you to install two PCIe NVMe U.2 2.5in SSD drives to your PC system via a PCIe 3.0 x8 card.
2. Parameter: Two SFF 8643 mini SAS HD connectors (requires the motherboard to support split function, only 1 interface is not supported). Interface: PCIE X8 to dual port SFF 8643. Hardware requirements: PCIe 3.0 x4/x8/x16, backward compatible with PCIe 2.0/1.0.
3. Throughput: Using sophisticated production techniques to support a maximum throughput of 32Gbps in PCIe 3.0.
4. Support System: Support for Windows2000, for , for server2003, for 64bit, for Vista, for win7, for , for DOS, for OS X.
5. Easy Installation: The adapter card can transfer 2 SFF 8643 interfaces through the PCle x8 slot of the host computer, and users can connect 2 U.2 SSDs at the same time through the SFF 8643 to U2 (SFF 8639) data cable (not included), with a bus bandwidth. Easy to install, no drivers required.

Specification:
Item Type: PCIE X8 to U.2 Adapter Card
Material: PCB
Interface Type: PCIE X8
Applicable : Conventional Desktop
Expansion Interface: Dual Port Mini-SAS HD (SFF 8643, 36 Pin) Female
Support System: for Windows2000, for , for server2003, for 64bit, for Vista, for win7, for , for DOS, for OS X
Hardware Requirements: PCIE 3.0 x8/x16, Backward Compatible with PCIE 2.0/1.0

packing list:
1 xPCIE X8 to U.2 Adapter Card
1 x Thin Bracket

Note:
The motherboard needs to support the split function, and only one interface is not supported. Note: Not all for BIOS systems support NVMe formatted U.2 drives, you need a for BIOS with UEFI. So check with your device manufacturer to make sure you can use it.