To overcome these limitations the induction heating industry turned to the inductor-generator. This type of machine features a toothed rotor constructed from a stack of punched iron laminations. The excitation and AC windings are both mounted on the stator, the rotor is therefore a compact solid construction which can be rotated at higher peripheral speeds than the standard AC generator above thus allowing it to be greater in diameter for a given RPM. This larger diameter allows a greater number of poles to be accommodated and when combined with complex slotting arrangements such as the Lorenz gauge condition or Guy slotting which allows the generation of frequencies from 1 to 10 kHz.