The 32oz Glow-Cup, Light is provided by a chemical reaction which takes place when two solutions are allowed to mix. To prevent the reaction from occurring prematurely, one of the solutions is stored in a very thin glass capsule which is easily broken by flexing or bending the tube. To activate the Glow-Product, squeeze the shape until all the inner capsules break, then shake, keeping the front of the shape face down. The glow lasts 4-6 hours.