SMD Magnetic Buzzer Advantages: 1.The volume of buzzer can be made very small.(Length and width can be made as 4MM). It can save lots of space. 2.Its sound is the highest in same volume product. Differences: 1.Current consumption is higher than SMD piezo buzzer(Common operating current should be within 100mA).However, its current consumption is still lower than speaker. 2.Voltage value of the product must correspond to the input voltage .And the external input square wave frequency must be same with the operating frequency of the product.(Except that customers need the function that it can make different tones.) SMD Piezo Buzzer Advantages: 1.Current consumption is very small.In general,it just need 2mA current when operating at 3V. 2.It can be used at any voltage between 3-20V. Differences: 1.The volume is bigger than SMD magnetic buzzer.Its sound is lower than SMD magnetic buzzer at same voltage . 2.The external input square wave frequency must be same with the operating frequency of the product.(Except that customers need the function that it can make different tones.)