What is classical free electron theory of metal?

Classical free electron theory is modeled by drude - Lorentz to explian elctrical conductivity in metals. According to this free electron in a metal (valence electron) move randdomly at room temperature and these free electron are drifted in opposite to the direection of the applied electric field. This is repsonsible for the conduction. Here all the free elctron are are considered as equal in all aspect.