Left to Right: Courier, StrapWrap, and TransPort All three of the cases have two things in common: first, they?re all designed to work with either the iPod touch or the iPhone, and second, each includes two Velcro-based rear flaps that open to let you place your bag strap inside, then fold over each other to grip the strap tightly while you?re walking. From there, they differ substantially in protectiveness, device accessibility, and other?