Functions and Selections MV: Overvoltage trip auxiliary, over-votalge protect: 270V5%.MN: Lowervoltage trip auxiliary, lower-voltage protect: 170V5%.MV+MN:When voltage overthan 270v, circuit breaker will trip to protect main power circuit;When voltage underthan 170v, circuit breaker will trip to protect main power circuit.When the line trips due to overvoltage or undervoltage, if you need to recover power, you need to pre the blue reset button to recover power.If the circuit is normally powered, pre the yellow test button to test whether the module is working properly. If the circuit breaker trips, the module is in good working condition. If the circuit breaker does not trip, the module may be damaged or the wiring is wrong. Please check or replace the module in time MX: Shunt trip auxiliary, can use voltage signal (DC24V, DC12V, AC220V, AC110V etc) to control the circuit breaker to trip quickly, which can realize the function of remote control and quick power-off.OF: Auxiliary contact, used to indicate the opening and closing status of the circuit breaker, and can also be used for fire alarm SD: Alarm auxiliary. When the circuit breaker trips due to overload, short circuit, leakage and other faults in the circuit, the auxiliary device outputs a signal. This device is mainly used for fire alarm. When the line fault is eliminated, the test lever on the device can be used to test whether there is a fault in the line. If there is no fault, the circuit breaker can be closed.OF: Auxiliary contact, used to indicate the opening and closing status of the circuit breaker, and can also be used for fire alarm OF: Auxiliary contact, used to indicate the opening and closing status of the circuit breaker, and can also be used for fire alarmAbout Shipping1, No more than 2kg weight:Shipping by Aliexpre Standard (20-35days)Shipping by China Post (20-35days)2, More than 2kg weight:Shipping by Aliexpre Standard (20-35days), China Post (20-35days), FEDEX (7-15days), UPS (7-15days), TNT (7-15days), other expre direct lines (10-20days). We will choose the appropriate logistics according to the actual situation3, Above delivery date is applicable for most cases. However sometimes parcels may be delayed fo holiday, festival, bad weather, custom, etc. Besides expre shipping ways may have tax iue. In those case, your comprehension and cooperation is highly appreciated4, Shipping ways and track website: Receiving and After-sales Service1, Please check the tracking information on tracking website2, Please contact us by meage, e-mail, or trade manager3, Check the package and item carefully4, All of our products are backed by a 12-18 month warranty in the event of non-human damage, please contact us and we will replace the product to youWe Need Your Support 1, If you visit our store for the first time, please click "Add Follow" button to collect our store, so that you can get the latest discount and new product notifications in time.2, If your are satisfied with products and our service, please leave 5 stars feedback.3, If your have any questions or problem, feel free to contact us first before you leave negative feedback.We will try our best to solve any problem and provide you with the best customer service