The Min/Max mode is as its name implies, it is the highest and lowest reading that the multimeter measured from the time the Min/Max record mode was started. Typically, they need the measured signal’s maximum or minimum to be 200 to 350 milliseconds long or longer to get an accurate reading. They work from any mode such as volts dc, true-rms volts ac, resistance, and current functions. Peak mode measures the positive and negative peak voltage of a signal. For the 120 volt ac line, the peaks will read +169 volts and -169 volts (120 V x 1.414 = 169 V for a clean sine wave). Typically they will work for peaks that are 250 microseconds or longer.