Guides
How to Choose a CFexpress Card Reader
Short answer: Buy a reader with a slot for your card type, CFexpress Type A or CFexpress Type B, and connect it to a computer port fast enough for the reader. This guide lists what to check; it does not recommend a particular reader. Lambda Grove cards do not include a card reader.
1. Match the reader to the card type
Type A and Type B are different physical cards. The CompactFlash Association says: "CFexpress Type A and Type B differ in physical size and maximum speed. Type A is smaller and uses one PCIe lane, while Type B is larger and uses two PCIe lanes".
| CFexpress Type A | CFexpress Type B | |
|---|---|---|
| Card size (CFA) | 20 × 28 × 2.8 mm | 29.8 × 38.5 × 3.8 mm |
| PCIe lanes on the card (CFA) | 1 | 2 |
| Reader you need | A reader with a CFexpress Type A slot | A reader with a CFexpress Type B slot |
A Type A card will not fit a Type B-only slot, and a Type B card will not fit a Type A-only slot. Look for the exact words "CFexpress Type A" or "CFexpress Type B" in the reader's specifications. Nikon's manuals add: "When choosing cards for use in card readers, be sure they are compatible with the device."
Our cards are described the same way: Type A cards are for cameras and readers with a CFexpress Type A slot, and Type B cards are for cameras and readers with a CFexpress Type B slot.
2. Check the reader's interface and your computer's port
A reader can only move data as fast as the slowest link: the card, the reader and the computer port. The CompactFlash Association lists the theoretical bus speed of CFexpress 2.0 as 1 GB/s for Type A (one lane) and 2 GB/s for Type B (two lanes).
When you compare readers:
- Read the interface the maker states, for example a USB or Thunderbolt connection, and check your computer has a matching port.
- Use the cable that comes with the reader, or one the reader's maker specifies.
- Expect lower speeds on a slower port. The reader will still work, but offloads take longer.
3. PCIe 4.0 Type A cards and readers
Our CFexpress Type A Memory Card - PCIe 4.0 also works in Type A cameras and readers built for PCIe 3.0, at that host's speed. For full offload speed, use a CFexpress 4.0 Type A reader on a fast enough port. The CompactFlash Association lists CFexpress 4.0 Type A at 2 GB/s.
4. Practical checks
- Card type: the reader's specifications name your card, CFexpress Type A or CFexpress Type B.
- Port: your computer has the port the reader needs.
- Eject safely: always eject the card in your operating system before you unplug the reader.
- Format in the camera, not the reader: use the reader to copy files, then format the card in your camera. Sony says: "Memory card formatted with a computer is not guaranteed to operate with the product." See How to format a memory card in camera.
5. Related products
CFexpress Type A and Type B cards carry a 5-year limited warranty; other products carry 180 days. See our Warranty Policy.
- CFexpress Type A Memory Card - PCIe 4.0 — for cameras and readers with a CFexpress Type A slot
- CFexpress Type A Memory Card - PCIe 3.0 — for cameras and readers with a CFexpress Type A slot
- CFexpress Type B Memory Card - PCIe 3.0 x2 — for cameras and readers with a CFexpress Type B slot
- CFexpress Type B Professional Memory Card - PCIe NVMe — for cameras and readers with a CFexpress Type B slot
Not sure which card you have? Read CFexpress Type A vs Type B vs SD, or check the Type A and Type B camera lists.
Sources (accessed 2026-10-30)
- CompactFlash Association, Card Types: https://compactflash.org/card-types/
- CompactFlash Association, form factor table: https://compactflash.org/wp-content/uploads/2025/07/CFexpress-Form-Factors-Website-2.png
- Nikon Z8 Reference Guide, Approved Memory Cards: https://onlinemanual.nikonimglib.com/z8/en/approved_memory_cards_385.html
- Sony ILCE-7SM3 Help Guide, Notes on memory card: https://helpguide.sony.net/ilc/2410/v1/en/contents/1001C_notes_on_memory_card.html
- Lambda Grove, CFexpress Type A Memory Card - PCIe 4.0: https://lambdagrove.com/products/cfexpress-4-0-type-a-memory-card
FAQ
Can one reader read both CFexpress Type A and Type B cards?
Only if its specifications list a slot for each type. Type A and Type B are different sizes, so a reader built for one type will not take the other.
Is a card reader included with Lambda Grove cards?
No. Our product pages state that a card reader is not included.
Will a PCIe 4.0 Type A card work in an older Type A reader?
Yes, our PCIe 4.0 Type A card works in Type A cameras and readers built for PCIe 3.0, at that host's speed. For full offload speed, use a CFexpress 4.0 Type A reader on a fast enough port.
Why is my reader slower than the card's rated speed?
Speed is limited by the slowest part of the chain: the card, the reader's interface, the cable and the computer port. Check that each one supports the speed you expect.
Can I format the card in the reader?
We recommend formatting in the camera. Sony says a card formatted with a computer is not guaranteed to operate with its cameras, and Canon, Nikon and Panasonic tell you to reformat cards in the camera.
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Guides
How to Format a Memory Card in Your Camera
Back up first, then format in the camera. Official menu steps for Sony, Canon, Nikon, Fujifilm and Panasonic cameras, with quick vs low-level format notes.
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Compatibility
CFexpress Type B Compatible Cameras: Canon, Nikon, Fujifilm and Panasonic
Which Canon, Nikon, Fujifilm and Panasonic cameras have a CFexpress Type B slot? A list checked against each maker's official manual or support page.
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Compatibility
CFexpress Type A Compatible Cameras: Model-by-Model List
Which Sony cameras take CFexpress Type A cards? A model-by-model list checked against Sony's official Help Guides, with recording-mode and format notes.
Read the guide