Transcend microSDXC/SDHC 300S latest Speed Class, boast excellent random read/write speed and perfect for retrieving small pieces of data from random locations and speeding app launch time.Transcend's microSDXC/SDHC 300S memory cards meet the new A1 standards, delivering minimum random read of 1,500 IOPS and random write of 500 IOPS, and sustained sequential speeds of at least 10MB/s.Transcend's microSDXC/SDHC 300S memory cards meet both the UHS Speed Class 3 (U3) and the UHS Video Speed Class 30 (V30) standards for 4K Ultra HD video recordings, with read/write speeds of up to 95MB/s and 45MB/s respectively., Transcend's microSD memory cards are tested to withstand extreme conditions. They are temperature resistant, waterproof, shock proof, X-ray proof, and static proof.