CompactFlash 
A small, removable device about the size of a matchbook, typically used to store images in digital cameras and to add memory to handheld devices. CompactFlash cards use nonvolatile memory, which means they don't require power to retain data indefinitely. CompactFlash cards come in two form factors: Type I (1.7 inches wide by 1.4 inches deep by 0.13 inches thick) and Type II (1.7 inches wide by 1.4 inches deep by 0.19 inches thick).