A flash memory format introduced in 1994 by SanDisk. At approximately 36x43x3mm, CompactFlash (CF) cards are much larger than the SD Cards used in most cameras; however, they are still used in digital SLRs, and many photographers find the larger size harder to misplace. CompactFlash supports both 3.3v and 5v circuits and can hold up to 512GB as of 2015. Data transfer speeds are designated as multiples of the first CD-ROM rate of 150 KB/sec. For example, 1,000x = 150 MB/sec. See CD-ROM drives. CF Cards Use the PC Card Interface Type I CF cards are 3.3mm thick and commonly used for camera storage. Type II cards are 5mm thick and were previously used for miniature hard drives, modems and Ethernet. On earlier laptops, adapters enabled the 50-pin Type II CF card to plug into the 68-pin PC Card slot. See Microdrive and PC Card.