The M-Audio CO2 is a handy utility that converts Optical to S/PDIF and vice versa. The CO2 features Optical to S/PDIF, and S/PDIF to Optical modes as well as a Bi-directional mode. The B-directional mode enables the C02 to be used as a repeater when using long cables. The compact rugged design proves both convenient and reliable in and out of studio enviroments.