Dice contained in pop-O-matic bubbles, the like of which are attached to famous board games such as Trouble. They are treasured by roleplayers for their supposed ability to deflect dice curses due to the bubble which acts as a kind of force field.
Most pop-O-matic dice, however, seem unable to gain the amazing luck that some dice free of confine enjoy. In fact, they tend to roll very randomly. While some gamers may balk at randomness, most will agree it is better than constantly skewering yourself with that Hackmaster +12 because the damned halfling sitting next to you decided to give your die the evil eye.