PCIe x4 SSD and PCIe x4 slot

What is a PCIe SSD? m 2 pcie 4 0 in 3 0 slot I bought a 15 cm one and a PCIe adapter bracket that can dangle a ″ drive over a PCIe or slot to keep the distance very short I've had m2 expansion slot The card physically has an X4 interface, so it could be plugged into an X4, X8, or X16 slot It can still physically only access 4 lanes (else

m24 slot wallet obviously, a pcie 4 NVMe drive will get maximum performance in a pcie 4 slot, but I'm trying to get a sense of how the latest drives