What does C10 U3 mean?
C is the abbreviation of class, C4 is the lowest writing speed of 4M, C10 is the lowest writing speed of 10M, the number after U multiplied by 10 is the lowest writing speed, U1 is the lowest writing speed of 10M, and U3 is the lowest writing speed of 30M. (Note that most of the price-oriented knockoff cards cannot even guarantee the 10M write speed). If you have certain expectations for speed, such as those who don’t want to wait for slow copying of files, or writing similar to full HD and high frame rate, U3 is required.