Size is as-packaged, or the diameter of loose marbles. ("D" is the diameter of round items other than marbles.)
Opalite (also called sea opal) is a synthetic gemstone made from glass. (The same glass is used to make Moonie
marbles.) You know because you can see the orange "fire" burning inside when you hold it to the light, just like
Moonies. These are peewees, just for fun! Adding a few peewees to the ring adds a bit of challenge - they are harder to hit.