CFexpress is a removable storage standard designed around a PCIe interface with NVMe protocol support. CFexpress cards come in three form factors which correspond to the amount of PCIe lanes, with 2-lane B cards being the most common. This form factor is 38.5 x 29.8 x 3.8mm with a maximum power draw around 3W.
Most typically these cards are used for high-bandwidth applications such as with photography and especially high-resolution videography. The Xbox S|X consoles also utilize CFexpress to enable high-speed storage expansion with NVMe support for DirectStorage as part of the Velocity Architecture.
The use of PCIe lanes allows for very high bandwidth, up to 1,700 and 1,500 MBps for reads and writes, respectively, on our cards. As this is through PCIe, these speeds are full-duplex. We offer TLC CFexpress cards up to 2TB in capacity with many of the perks SSDs enjoy, including endurance management, upgradeable firmware, and TRIM support.
For more information on speeds and other specifications, please see Wikipedia's page.