We have bought two of these.  You get an open slot with your smartphone and you should use it.  Pictures, movies, and music will fill up your primary device storage in a heartbeat.  Further, it is a good practice to have your &#34;personal&#34; stuff, like the things I just mentioned, saved to an external drive so as to not be in the mix should the horrific happen and you have to get your phone wiped.Word to the wise:  ENCRYPT YOUR STORAGE, both Primary Device and External SD.  For the Samsung Galaxy S4 (at least), that, in turn, requires that you use a phone unlock code of at least SIX characters, with at least one of them being non-numeric.  I know this can appear to be a pain in the butt, but the first time your device is ganked and you aren't panicking because your stuff is encrypted, you'll thank me.  Nekkid pictures aren't the only things of concern, mind you.  An unencrypted device, stolen by the wrong hands, isn't just $25 in crack cocaine money...it is much, much more than that in terms of lucrative identity theft opportunities.  Don't be &#34;that guy&#34;.  Encrypt your phone.  There are walk-throughs showing how to do that for whatever device you happen to have on YouTube, I am certain.