SD Specification 5.1 establishes a new Application rformance Class that’s engineered to run mobile apps with comparable performance to using your phone’s internal storage.  Android Marshmallow brought support for adoptable storage, which allows you to merge a phone’s internal space with a microSD card. But some are vexed by cards that offer slower performance than the phone’s hardware, which can slow things down for more resource-intensive applications like mobile games. SD 5.1 offers a rating for App rformance Class 1, or A1. Cards that show this symbol will meet or exceed the following performance levels: 

Rom Read Input-Output access r Second (IO) of 1500 ite IO of 500 Sustained Sequential performance of 10MB/s.

You can look for the following symbols on the packaging to ensure you’re getting an SD card with the right performance capabilities: If you want to read up more on what the SD Association has created, you can dig into a white paper that offers more details. y this matters: ile moved away from offering external storage with last year’s Nexus phones the new xel, high-end phones like the Galaxy S7 line many budget models still offer SD storage. It’s been a fine choice for storing your photos or music, but putting apps on your SD card has been a dicey proposition. This new spec labeling system should help those in the market for one make a better buying decision.