It will make your hair stand on end! Made from highly polished stainless steel that resists corrosion and oxidation, this mirror-smooth and seamless, negatively-charged globe makes learning about static charge exciting and interactive. The smooth surface makes for very few discharge points. A true sphere measuring 12-5/8 in. in diameter. The cover of the base that protects the inner workings of the machine is made of black plastic which insulates the motor and resists draining the charge. The column is 3 in. dia. made of shock-resistant, transparent butyrate. Sparks can reach up to 10 in. Operates in humidities up to 90%. 400,000V potential. Entire unit measures 29 in. H.