microSD Speed Class (A1 / A2 / U3 / V30)

microSD cards carry several ratings: the A-class (A1, A2) guarantees random-access performance, while U3 and V30 describe sustained sequential speed. For handhelds the A-class is the one that matters, because loading games is random I/O — A1 sets a floor most libraries never exceed, and A2 raises it but needs host support to show real gains. U3/V30 matter more for high-bitrate video capture than gaming. Buy a reputable A1 or A2 card sized to your library; the top V-rating is usually not the point.