NO EXTERNAL MEASURING DEVICE NECESSARY! The built-in voltmeter can measure the input or output voltage and show it on the display. With the measurement error correction function, the accuracy of the voltmeter can be adapted to your own requirements VOLTAGE REGULATION AND VERSATILE DEVICE: The trimmer enables precise setting of the output voltage from 3.3-24V. The module can be used from an input voltage of 4V. Particularly practical for the simultaneous use of different microcontrollers, a 5V power supply can be reduced to 3.3V COMPACT DESIGN: The design guarantees permanent operation with an amperage of 2A, in combination with additional cooling, up to 3A can be called up Material:plastic colour:Blue Package Contents: 3 x Buck Converter Module Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.