A rare inclusion in a marching band that is becoming more popular is the use of electrophones in a marching band. The most common electric instrument seen is a bass guitar, but some schools also use keyboards and lead guitar. To make the electric instruments usable, external power in the stadium is often used, but some groups may use a car-battery mechanism that requires a car battery and a converter to give the instruments and amplifiers remote power. Also, some groups may use a small gasoline-powered generator.