CompactFlash cards (also known as CF Cards), was originally a popular storage device for digital cameras. In the past few years it has been replaced by smaller cards on the consumer end, but it is still a preferred format for D-SLR cameras, for its superior capacity and reliability. The Compact Flash speed rating refers to the speed the camera or data is written to the card. Most CompactFlash cards are speed rated and come in standard speeds such as 40x, 80x, and 133x. The X represents the transfer rate, and 1x means the card can perform data transfer at 150 KiloBytes (KB) per second. High Speed CF cards are a brilliant investment for any photographer. Besides enhancing in-camera functions and greatly reducing photo transfer time, you get the added enhancements of security and memory features that make selecting a high-speed memory card an easy choice. If you're not using a speed-rated memory card, now's the time to make the switch! There are two main types of CF cards, Type I (3.3 mm thick) and the thicker Type II (CF2) cards (5 mm thick). CompactFlash cards are currently available in capacities from 512 MB to 32GB. At the beginning of 2008 Samsung launched 16, 32 and 64 GB CF and Pretec announced 48 GB cards soon after and 100GB cards in September.