SM2 series  is an all new high performance current device with the ability to disconnect short circuits of up to 10KA,which is the neweast model in 21st century,SM1 MCB has many merits of high protective grade(up to IP20),high breaking capacity.good reliability of sensitive action,convenient mulit-pole assorting, long using life etc.they are main ly used for overload and short circuit protection within the circuit of AC 50Hz,230V in single pole, 400V in double.