Class rating in Memory cards....understand before buying a new one...

You may have heard or seen speed ratings starting to appear on SD, Micro SD and Mini SD memory cards, these ratings are split into three categories as defined by the Secure Digital Association (SDA). These categories were introduced to make it easier for the consumer to identify the minimum speed capabilities of their SD cards. The three categories are defined in the below table:

		Transfer speed is a minimum of 2MB/sec.
		Transfer speed is a minimum of 4MB/sec.
		Transfer speed is a minimum of 6MB/sec.
		Transfer speed is a minimum of 10MB/sec.

Previously different manufacturers have indicated data transfer speeds in various ways and there has been no standard. The existing speed ratings in use state the memory cards maximum Data Transfer Rate (DTS) which may vary, the new SDA version 2.0 speed rating states a guarantee minimum sustained DTS.
The new SDA class ratings will be adopted by all memory card manufacturers which will make life a lot easier when comparing different brands. Speed classes logos will appear near the SD cards logo as shown on the below Sandisk SDHC 32GB memory card which is a class 4:
As technology moves forward devices such as Digital Cameras and Digital Video Recorders are requiring higher specification memory cards. Manufacturers of these host devices are now starting to stipulate the appropriate speed rating class to achieve the best performance. Having this information readily available and in an easy to understand format is definitely a great step forward and will save us all a lot of time researching what is the best memory card for my Camera!