Glow Discs are the same as their non-glowing counter parts with the exception of a phosphorescent additive to the plastic. This substance allows the disc to emit a soft glow after being exposed to light, particularly ultraviolet or infrared "Black Light". Glow discs were created so players could play at night and still be able to find their discs. Night Golf or "Glow Golf" is particularly popular in the Fall when time changes bring nightfall very early. If players want to throw after work it's going to have to be Glow Golf.