I bought the 64GB Ultra card to increase storage on my Acer A500 Android Ice Cream Sandwich 4.0.3 tablet.  It didn't work as Android doesn't support its native exFAT formatting from the factory.  Insert the card into an SD adapter and plug it into a PC or Laptop under real Windows.  Reformat this card to the NTFS format with Windows Format utility and Android can then read and write any size file, even files over 5GB, to and from this card.  You do NOT need to root or modify the Android tablet in any way, except to have ver 4.0.3 operating system on it.  This product is very fast reading and writing and has proven very reliable...a great value in some really serious storage space.