HumphreyLine offers a wide range of plastic glow-in-the-dark products, including flyers in all three sizes, stadium cups in seven sizes, the all pro yoyo, the pint and quart bottles, and three sizes of sand pails. All of these items are made in our factory in Kentucky. HumphreyLine's glow-in-the-dark flyers and yoyos are all child safety tested. The glow comes from an additive that we blend into the plastic resin, and it will hold its glow for hours, once it is recharged in light. If the item is kept in a dark place and then recharged in light, the glow affect will work for years.