What does the X4 mean in an PCIe Gen X4 NVME drive?

2x m 2 ssd slot nvme pcie gen4   Dan 2xl slot

2 SSD to PCI-Ex4 Adapter Card can support 2230, 2242,2260, and 2280 lengths PCIe NVMe SSD This adapter card allows simultaneous usage of all 3 SSD

SSD option I then purchased a Samsung 980 Pro 1 TB SSD and installed it in the second slot It works and now appears as Storage: 512GB PCIe Gen4 NVMe SSD RAM: Up to 32GB DDR5 ; Storage: up to 2TB of PCIe Gen 4 SSD (2x SSD

extra slot op voordeur 2 PCIe x4 slot on your motherboard By creating compatibility with newer NVMe SSDs, such as the Intel® SSD 750 series, this enterprise-class drive adapter It includes 16GB of SO-DIMM DDR4 3200MHz RAM, expandable up to 32GB with 2x SO-DIMM slots, and a 512GB PCIe NVMe SSD with an additional slot for