Small internal extension cards with the M.2 form factor can be inserted straight into a system port. It is most frequently found in solid-state disks (SSDs), but Wi-Fi, Bluetooth, or NFC extension devices are also frequently added. A computer network link for up to four PCI Express lines, one SATA connector, or a USB connection is provided by the standard. Similar in appearance to a memory module, an M.2 card has connection ports on its short side rather than its long side.

The M.2 standard is most frequently connected to NVMe SSDs even though it allows storage devices using a traditional SATA interface. For greater capacity and decreased delay, NVME disks make use of numerous PCI Express channels, providing read-write rates of up to 3.5 GBps (compared to 600 MBps over SATA).

Measurements and Keys

A motherboard's M.2 slots are marked with one or two grooves, which are identified by symbols that designate where they are located. The "A" notch takes pins 8–15, "B" removes pins 12–19, "E" removes pins 24-31, and "M" removes pins 59–66. The slots' supported card types are indicated by the grooves. Wireless devices that add Wi-Fi, Bluetooth, or NFC transmitters can be inserted into the slots marked A or E. SSDs can be inserted into spaces keyed B or M at varying rates; spots marked M can accommodate speedier disks.

The normal measurement limit for M.2 cards is indicated by a 4- or 5-digit number. The concluding two or three numbers represent the length, while the first two digits represent the breadth in millimeters. A tiny Wi-Fi device, for instance, might be 2230 in size (22 mm broad and 30 mm long), whereas an SSD might be 2280 or 22110 in size. It is essential to know what sizes the motherboard allows before inserting a card because the end of an M.2 card must fit into a matching opening on the motherboard.