If you compare an Olympic medal with a Paralympic medal, then you will notice that there are more differences to them than just the design. Instead, the medal for the Paralympics is rather ingenious in what it is able to do.
In those games, there are a number of individuals that have issues with their sight, so they do not want to have them feeling as if they are missing out on something when they win a medal and just because of their sight. So, it was decided that apart from the design of the medal that there would need to be something rather special.
What this led to was a medal that contained steel balls inside that rattle when you shake them. There are different combinations depending on the color of the medal that you receive, but it allows the visually impaired to tell the difference between the medals. They no longer have to feel as if they are missing out on something as a result of their disability.