We all have products that use the Secure Digital Cards. SD has been adapted by nearly all consumer product makers in one form or another. Which form is another story entirely, as there are so many and within each category there are speed ratings. Some devices need to be able to operate above a certain speed to be able to handle the tasks given. This is where the class structure comes in.

Most storage products are rated at a maximum speed, the highest peak performance possible under ideal conditions. This works out well when everything you are doing is well within specifications, but there can be times when a minimum speed is required. SD products are rated at a minimum speed, the Speed Card Rating. A Class 2 SD card can write at least 2MB/s, a Class 4 SD card can write at least 4MB/s and so on. Devices like HD video recorders require a minimum sustained write throughput. If your device needs to be able to write at 6MB/s but can only write at 4MB/s, then your video will suffer from dropped frames, lost audio or be completely corrupted. Currently Class 10 is the fastest available on the market and it has a minimum speed of 10MB/s.



Link: TweakTown