Imagine rolling a bunch of these beasts every time you made a 10d6 energy blast! Somehow, rolling 10 d6s that are 7/8" wide seems a lot more fun than rolling 10 of those 12mm ones. They're only about twice as wide, but (volume-wise) it's the difference between approximately 6.7 cubic inches, and a little over 1 cubic inch. That's almost 7x more volume (if my math skills aren't failing me miserably right now).
In case you're wondering, I think it's the die from a copy of Seinfeld Scene It, and it showed up in a box of crap somebody brought to my semi-recent garage sale.