With image files quickly growing in size, the time it takes to store or write those files to a Flash card has become increasingly important to buyers. Today, many Flash cards are sold with an “X” speed rating, giving users a performance indicator of how fast the card can transfer images.
First of all, it’s important to note that manufacturers define this rating differently and in some cases do not define it at all. Some definitions refer to the X-speed as “read” speed or “write” speed. Others use it to mean both and call it “data transfer” speed.