This is a great little wallet-sized dice roller. I use it often when getting out my dice would be inconvenient, and I don't want to use an app. Great work Mixed Signals! I do keep a coin in my wallet with the pocket dice roller. When I need a d20 roll, I "roll" the d10 and I flip the coin. On a heads I add 10 to the d10 result (and count the '0' as a '10'). Same principal for d12s, just add 6 instead.