The A1 symbol on Micro-SD cards tell you if it is fast enough for apps - NotebookCheck.net News
A1 vs A2 SanDisk MicroSD Card: What's The Difference? - MyMemory Blog
Are high-speed/high-capacity (A1, A2, U3) microSD cards worth it for Android? With Black Friday and Cyber Monday deals coming up, I (re)tested 5 of those and 2 older ones in 3 quite
A1 VS A2 SD Card: Compare Them and Make a Wise Choice - MiniTool Partition Wizard
A1 VS A2 SD Card: Compare Them and Make a Wise Choice - MiniTool Partition Wizard
microSD Cards "Application Performance Class" - A1 and A2 Ratings, with the RPi - Raspberry Pi Forums
A Guide to Speed Classes for SD and microSD Cards - Kingston Technology
What determines whether you should use a Sandisk A1 or A2 micro SD card for more storage on Android phones? Is the A1 better if not storing photos/videos? - Quora