This was the fastest microSD card I have tested, unfortunately it died after about four months of use in my Android phone. At first my phone would randomly say the card had been removed, then eventually neither the phone nor any reader I had could access it.The test results from my older but still functional 32gb class 4 sandisk:Sequential Read :  23.022 MB/sSequential Write :  4.460 MB/sRandom Read 512KB :  22.387 MB/sRandom Write 512KB :  3.144 MB/sRandom Read 4KB (QD=1) :  3.414 MB/s [  833.5 IOPS]Random Write 4KB (QD=1) :  1.231 MB/s [  300.5 IOPS]Random Read 4KB (QD=32) :  3.309 MB/s [  807.8 IOPS]Random Write 4KB (QD=32) :  0.993 MB/s [  242.4 IOPS]Compared to this product, 32gb class 10 sandisk:Sequential Read :  41.492 MB/sSequential Write :  15.653 MB/sRandom Read 512KB :  43.380 MB/sRandom Write 512KB :  17.685 MB/sRandom Read 4KB (QD=1) :  4.696 MB/s [  1146.5 IOPS]Random Write 4KB (QD=1) :  1.595 MB/s [  389.4 IOPS]Random Read 4KB (QD=32) :  4.859 MB/s [  1186.2 IOPS]Random Write 4KB (QD=32) :  1.334 MB/s [  325.6 IOPS]