Steven K
I purchased this product knowing there might be an issue with the galaxy s4. This card worked for a week or two then began to spontaneously unmount and would mount itself back in. The unmount periods began to become longer than a few hours, days! I tried this card in a galaxy note 2 still with the same result. I attempted to contact Sandisk customer service and utilize the warranty. They know of the problem and began the exchange process then instructed me to wait for a mailing label that never came. I called back and was told that they would re-email it to me. To this day I am still waiting for that email. I have never had this issue with this company but with  ever changing technology, it is what it is, right? I know this card will be good for some device I have. If you own a galaxy phone beware!! I have not attempted to use this in a samsung tablet so on that I cannot review.