UHS-I U3 memory cards

UHS-I Class 3 (U3)

— first generation UHS cards that provide Class 3 recording. First generation (UHS-I) provides read speeds up to 104 Mbps from the card (in earlier versions this speed was lower, but these versions are practically not used in modern cards). And Class 3 compliance means that the write speed to the card (when working via UHS) is at least 30 MB/s. This speed allows to shoot 4K video at a frame rate of up to 120 fps (depending on the codec), 8K video at 30 fps and Full HD video at 120 fps.

Note that the actual minimum requirements for UHS Class 3 are the same as for V30 video recording (see relevant paragraph). However, among cards belonging to Class 3, there are also higher video recording classes — V60 and even V90. There is no contradiction here: the guaranteed write speeds supported by such cards (60 MB/s and 90 MB/s) are quite consistent with the “not less than 30 MB/s” criterion for UHS Class 3.