16GB Kingston - class 4 - micro SD (Amazon '#1 Best Seller') = 4:30 @ about 5 MB/s16GB SanDisk Ultra - class 10 - micro SD = 2:15 @ about 10MB/sResults from my informal data transfer test. Copied a large 1.3GB video file to my two micro SD cards.This SanDisk Ultra takes about half the time to transfer data. Time is money and I'm happy with the results considering the current Amazon price is about $11 vs $14 for the SanDisk Ultra.