Class 6 microSD card?

[Dapman02]

What does a class 6 microSD card mean, My buddy wants it for his blackberry

[meionm]

SDHC cards have SD Speed Class Ratings defined by the SD Association. The SD Speed Class Ratings specify the following minimum sustained write speed on to empty SDHC cards:

Class 2: 2 MB/s
Class 4: 4 MB/s
Class 6: 6 MB/s