I had a Sandisk 4GB Extreme III Compact Flash card for my Canon 5D M2 and was concerned that the 20MB per second wasn’t fast enough to record the 1080p videos that the camera is very capable of making. So I upgraded to an 8GB Sandisk Extreme IV Compact Flash over Christmas. If you have a digital SLR, particularly the Nikon D90 or Canon 5D Mark II that shoots video, I highly recommend it – its maximum write speed is a whopping 40MBps!
The SanDisk Extreme IV has extremely fast read/write speeds. This line provides the durability, high-speed, and quality demands for serious photography. The SanDisk 8GB Extreme IV CF Card is the new industry leader in the best-in-class solution for high profile professional photographers. (I’m not a professional, just want the fastest 
)
Features of the Sandisk Extreme IV Compact Flash 8GB Card:
- Industry-leading choice
- Professional grade capacity and speed
- UDMA enabled — turbocharge your data transfer rates without draining your device’s processor
- Quality tested under the harshest temperature, shock & vibration conditions
- Add a FireWire Reader (sold separately) to further accelerate your workflow
- Priority technical support online/via telephone
- Built-in trust with a limited lifetime warranty*
