A good fit for mobile app storage itâs common for users to install and run mobile apps from microsd cards in order to free device memory. Random read write performance is thus crucial. Transcend's microsdxc sdhc 300s memory cards are a great fit for storing mobile apps. Introducing application performance class the application performance class was introduced to adapt this new trend. 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. Show the transfer capabilities 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 40mb s respectively. Store as many as you wish in addition to excellent random read write performance, transcend's microsdxc sdhc 300s memory cards come in up to 512gb storage capacity, allowing you to keep more digital files and apps at hand! Built for extremes to deliver the best performance and stability, transcend's microsd memory cards are tested to withstand extreme conditions. Waterproof meet jis ipx7 standards that can withstand immersion in 1 meter of water for up to 30 minutes. Temperature proof perform in temperature extremes from 25Â°c to 85Â°c. Static proof meet emc iec61000 4 2 standards and withstand static electricity. X ray proof meet the iso7816 1 standard and are immune to airport x rays. Shock proof provide excellent shock, vibration, bending and twisting resistance. Specification speed class uhs i u3, uhs i u1, class 10 , v30, a1 sequential read write crystaldiskmark 512 gb 95 40 mb s, 256gb 95 40 mb s, 128gb 95 40 mb s insertion removal cycles 10,000 operating temperature 25Â°c 13Â°f 85Â°c 185Â°f operating voltage 2.7v 3.6v note speed may vary due to host hardware, software, usage, and storage capacity.