Collection of glow bracelets. These are ring-shaped tubes containing two chemicals and a dye. The chemicals are biphenyl oxalate and, in a small glass vial, hydrogen peroxide. The fluorescent dye (fluorophore) is mixed with the oxalate. When the vial is broken, the peroxide mixes with the oxalate a chemical reaction takes place. This causes the fluorescent dye to glow in a specific colour. The reaction can take many hours to complete, meaning the bracelet will glow for a long time.