With a maximum write speed of 495mbs and read speed of 560mbs the delkin 256gb cinema cfast 20 card is hd ultra hd dci 4k video ready and is suitable for professional photographers and videographers the fast transfer speeds ensure the quickest most efficient data transfer from card to computer and each card has undergone an extensive series of tests to guarantee full functionality and performance in the latest cinematic hosts from canon blackmagic atomos among others