This ball is a glow in the dark Nee Doh ball. Hold it up to the light to activate it, then turn out the lights to watch it glow! The ball is about 2.5" when it is round, but can be stretched out! This is very calming because it has a very silky soft feel, and it is filled with a thick soft almost fluffy doh that looks like soft serve ice cream. You need to feel it to really know how nice these are.