Crystal Disc Mark is for bench marking the performance of a storage device. This can be a hard drive, memory card, or usb device. Basically, it just gives you a display of the read/write transfer speeds. Just start the app and select your drive. You can lower the amount of data to be tested to shorten the length of the test with SD cards or USB devices. I tested a few regular SD card, not a high transfer rate SD card, and found about a 13 to 15 MB/s transfer rate.

Download - Crystal Disc Mark 3.0