METR-MA2115S is a multifunction AC/DC test and measure module that can be used in combination with certain multimeters and testers from Metrel. It features an AC/DC frequency and true RMS measurement range of 5 Hz to 1 MHz, along with a wide range of other functions, including peak hold, low pass filter, auto sequence, relative value comparison, and analog bar-graph. It also has a host of safety features including shock, overvoltage, and reverse polarity protection. The unit is powered by a single 18 V battery and is designed for applications in harsh industrial environments.