... this series have low power,but it have complite protection,such as over-current,over-voltage,over-temperature,overload,DC and ... so on.so the series have 2 defferent uses.SPECIFICATIONS ... Ratio90dB90dB95dBInput inped.(bal/unbal.)20KΩ/10KΩProtectionOverheat,short ciruits,DC,limit and softstart,Output Relay -Zero CurrentSwitch,Intellectual ...