16GB card. down after a third use, about 2000 photos with a Canon 5D MkII. In the fourth formatting, blocks and nothing goes. My Canon says "defective card". My 5D and 50D do not recognize the card. On the PC, you can not access photos and can not be formatted. This is the first CF card let go for about 7 years. I mostly use the 4GB and 8GB. Amazon asks me to contact Sandisk for the guarantee. For now I exchanged emails ... I hope to exchange the card ...