Short for secure digital high capacity, the SDHC card is an improved version of the standard SD card with a storage capacity up to 32 GB. Because SDHC works differently then a standard SD card, it is not backward compatible with legacy SD devices.
The 3 versions of the SDHC card, with their physical dimensions, are shown below.
- SDHC - 32mm x 24mm x 2.1mm.
- Mini SDHC - 21.5mm x 20mm x 1.4mm.
- Micro SDHC - 15mm x 11mm x 1.0mm.
What is the Class Speed Rating?
The SD Association created three speed classes that help identify the write speed for SDHC cards. This Class Speed Rating is shown on the card as a 2, 4, or 6 surrounded by a large "C." In the above picture, you can see the 2 surrounded by a C on the first SDHC card. Below, is a break down of these speeds.
- Class 2 = 2 MB a second.
- Class 4 = 4 MB a second.
- Class 6 = 6 MB a second.