ThinkGeek Radioactive Elements Glowing Coaster Set - Radium, Plutonium, Uranium, and Thorium - Set of 4 CHEMISTRY-PERFECT - Put the elements from the periodic table to your table. Enjoy a glass of your favorite beverage and place them in these chemistry-inspired coasters featuring the symbols of Radium-226, Plutonium-244, Uranium-238, and Thorium-232. COASTERS THAT LIGHT UP - The coasters light up when you put your drink on them. Included in the pack are eight 3V CR2032 batteries. With constant use, these batteries can last up to 4.5 hours. GREAT AT PARTIES - These coasters are ideal for parties. You will easily remember which drink is yours. IDEAL PRESENT - This is an ideal present to the Chemists in your life, be it a family member, a friend, or a colleague. MADE BY THINKGEEK - The Radioactive Elements Glowing Coaster Set is a ThinkGeek creation.