Sonnet 2x4 Low-profile PCIe Card

There are other devices available which can allow up to 4 NVME drives at x4 in an x16 slot

PCI-SIG also authored standards for SSDs, which provides PCIe connectivity for small form factors and is designed for internally mounted expansion cards

m2_1 slot 2 slots support only PCIe SSDs Combo SSD slots support both interfaces so you can use either a SATA SSD or a PCIe SSD with them NVMe is

m2 nvme slot According to wikipedia M keyed means PCIe ×4, SATA and SMBus So a M-keyed port can do both PCIeNVMe and SATA