Starting at 4 GB, SDHC cards offer larger-volume data storage and optimized recording performance with support for FAT 32 file formats. In addition, Kingston's SDHC cards use a new speed "class" rating known as Class 4 that delivers a minimum transfer rate of 4 MB/sec. for optimum performance with SDHC devices. Although identical in size to today's standard SD card, the new SDHC cards are designed differently and are only recognized by SDHC host devices. To ensure compatibility, look for the SDHC logo on cards and host devices (cameras, camcorders, etc.). For added reliability and durability, our solid-state SDHC memory cards are built of nonvolatile memory components and have no moving parts that could wear out or break. All cards are 100-percent tested and are backed by a lifetime warranty† and 24/7 live technical support. Some of the listed capacity on a Flash storage device is used for formatting and other functions and thus is not available for data storage. As such, the actual available capacity for data storage is less than what is listed on the products - 1GB=1,000,000,000 Bytes. In OS system, it would be displayed as 1,000,000,000 Bytes/1024/1024/1024 = 0.93GB - *PLEASE NOTE Class 4 cards may not support HD recording in your device. Please check your device specification and requirements.