Input voltage: DC 4 V to 40 V. The input voltage must be more than 1V higher than the output voltage. If the input voltage is lower than 4 V, the voltmeter does not display Output voltage: DC 1.25 V to 37 V voltage continuously adjustable, output current 2 A, maximum 3 A High efficiency: 150 kHz internal oscillation frequency, low power consumption, high efficiency. The conversion efficiency is up to 92%. The input terminal is protected by a diode and the module will not be damaged if connected . With overheating protection and short circuit protection Easy to use: Press and hold the switch for more than 1 second within 4 seconds and release it to turn off the voltmeter. Simply press the switch to turn it on again. The indicator light can indicate that the IN/OUT voltage is measured. Note: This is a module. The input and output interfaces cannot be reversed. The input voltage must be higher than the output voltage. A heat sink is required for long-term work over 2A/15W. For the first time, you need to turn the potentiometer more than 10 times counter-clockwise. Material:plastic colour:blue Package Contents: 5 * LM2596s downward converter 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.