Purchased for my android phone to provide more media storage.  The one I received was DOA.  Spoke with SanDisk tech support who confirmed that it was a bad unit.  Since it was within 30 days, they suggested I return it to Amazon instead of going through warranty procedures.  I returned it to Amazon, but made the mistake of requesting a replacement instead of a refund.  The replacement appeared to work at first, but after a short while, it caused my phone to reboot, files went missing and displayed other forms of instability.  It was a bit late to return again, so I contacted Sandisk who replaced the unit under the warranty.  However, this all took a lot of time, necessitated repeated copying of many GBs of data and secure erasing of information.The warranty replacement from SanDisk works well, so far.  However, I'm not seeing much improvement in my application over a similar 32GB Class 4 SanDisk microSDHC (this one is class 10).  Would probably give the current unit 3 stars, but this rating is for the Amazon delivered units (both defective).If you do get a bad one, I'd suggest to return for refund, not replacement.