... being broken. With super stable characteristic of physics and chemistry, long lifespan, it can be updated used. 3. Safe to surroundingNontoxic, free ... No contaminationto environment.4. Fast charging, long glowing Being charged by lights for 15~20mins, it glows in dark place for 12hours ... or hot, rainy or thirsty, UV light or visible light, charge it to give luminous.-20~120oC, 0~100% humidity, the signs ...