SanDisk Extreme 4GB CompactFlash Memory Card Speed Up To 40MB/s- SDCFX-004G-X46Power Core Controller for Outstanding Performance The SanDisk Extreme CompactFlash Memory Cards feature Power Core Controller and Enhanced Super Parallel Processing Technology, which distributes image data across the card more rapidly and efficiently to take whatever your camera's buffer can dish out. The card features read write performance speeds of up to 60 MB s (up to 40 MB s for the 4 GB card) to capture more continuous burst shooting. It is UDMA