Empire USA Billiard Glow in the Dark Ball Set, 2.25-Inch Set of high quality billiard ball, made by high quality resin, each ball are polished to perfect balance of roundness; Each ball are made to 2-1/4" which is the standard size worldwide All balls will glow in the dark without a black light They will need to sit under light for a moment before they start to glow in the dark