M.2 is also a flexible connector.

M.2 not only supports SATA, but also PCIe (Peripheral Component Interconnect Express), although not at the same time in a given M.2 SSD. It even supports USB 3.0, Bluetooth, Wi-Fi and Near-Field Communication (NFC) in certain configurations.

Upon closer examination of an M.2 module, users may notice that there are notches, or keys, where the connector pins are located, yielding asymmetrical pin configurations. These determine which interface the M.2 module uses and the bus (PCIe, USB 3.0, etc.) that it can connect to. It’s also a design that prevents slotting an M.2 card into an incompatible interface or placing it in a reverse configuration.
M.2 SSDs are capable of attaining high data transfer speeds, but it all hinges on the type of storage interface used.
A SATA-based M.2 SSD is limited by SATA’s maximum limit of 600 MB/s (megabytes per second). An M.2 SSD that supports PCIe enables it to use NVMe (Non-Volatile Memory Express), a low-latency host controller interface specification that reach speeds of up to 4 GB/s (megabytes per second), delivering comparatively blistering performance on compatible motherboards.

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