SFF 8643 to PCIe 4X Adapter converts the PCIe interface on the motherboard into a U. 2 or connects the high-performance 2.5" NVMe U. 2 (SFF-8639) SSD to the computer motherboard. You can add a PCIe NVMe 2.5 in SSD to a computer system that doesn't support U. 2 PCIe NVMe.