I mainly purchased this for the armband b/c I'm training for a half marathon and wanted to use GPS and listen to music from my iPhone 4 while running. I had purchased a different armband from another store, and it didn't even have a whole in the top for earphones. This armband adjusts easily and could fit almost all size arms b/c it's got three large velcro spots. It doesn't slip while running. I use the band with the case still on the iPhone, so it's a bit too snug - but I don't want to take the time to take the plastic case off each time and would rather have it that way. The plastic case is good too b/c it protects the back from being scratched (the free bumper case did not and easily could get scratched when throwing it in my purse near keys) but isn't heavy or bulky.