Make your own (cheaper) CFexpress Type B cards with this NVMe SSD to CFexpress Type B adapter: Digital Photography Review
DELOCK 90349: PCIe x1 card with 2x SATA HDD - SSD at reichelt elektronik
Verbatim SSD ExpressCard 64GB Review: Unlock the potential of that unused ExpressCard slot on your laptop by adding up to 64GB of SSD storage, courtesy of the Verbatim SSD ExpressCard - PC
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NVMe M.2 M Key PCI Express x16 Adapter Karte | für SSD | Mac Pro | Mit Kühler | eBay