- The ForsusTM FRD is a flexible fixed functional appliance developed by Bill Vogt in 2001 that can be used with a fixed pre-adjusted Edgewise appliance. - It consists of spring modules, push rods of varying lengths, split crimps, and a measurement gauge. - The ForsusTM is recommended for Class II cases where patients did not cooperate with class II elastics, and is planned from the beginning of treatment.