answer:The phones – it depends on the phone. If you have an Android, and store app info on there, you’ll probably want to copy it over onto the new card, otherwise you’ll have to start all over for a lot of apps. But if it’s a phone where you just store pictures and music and ringtones and videos and documents, then you don’t have to copy (although I find it to be much easier). You have to use the proper size – you can’t use a microSD in a miniSD or regular SD slot.