The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
Four Dice is a simple utility that does what it says on the tin. It gives you four dice, and random dice rolls for each one. A re-roll is as simple as the tap of a button. Perfect for situations where you need to use dice but don't have space.