The Markbass MoMark EQ4 Bass Amp Module fits inside the MoMark unit as an optional component. The EQ module offers 4 bands of equalization set at the same frequencies as the EQ controls of the popular Little Mark II amp head. The frequencies that you can cut or boost have been carefully selected to be practical, and all tweaks are audible. Only small adjustments control punch, attack, and definition to suit your personal needs and tastes.