Krypton Thinking Putty DEFINES eerie, outer-space, alien, radioactive green! Charge with sunlight or our Blacklight Keychain for fantastic brightness! Wakeup before sunrise to see it glowing hours later! Glow in the Dark Thinking Putty is hypnotic and irresistible! Milky white in daylight, their glow magically appears when the lights dim. You can use our Blacklight Keychain to write messages on the putty and draw special designs. You can even do cool tricks with Glow in the Dark Thinking Putty. After exposure to light (the brighter, the better), these colors will glow for hours. Each metal tin is hand packed with 1/5 lb of Thinking Putty.