Don't think of these cards as the same, delicate pieces. The exact opposite. There are big variations in the output produced and the process is about efficiency and recovery. Product labeling is based on post-production testing taking them into the bucket. The raw product is a commodity and the quality and quantity of what is available on the market varies. One commentary describes a particular memory card vendor as "catcher of the day". Thus, the performance of a particular MicroSD card is unlike a specific SD card from another manufacturer to an "same" card from the same manufacturer.