brand new and high quality brand new and high quality LM2577S + LM2596S dual chip modules, DC-DC step up step down module with wide voltage design, suitable for solar panel and other high fluctuation external input power supply Appearance Size: Approx. 6.6 x 4.7 x 1.4cm / 2.6 x 1.85 x 0.55" Step-up Mode: Input 3.5-28V, output: 1.25-26V Output voltage is irrelevant to input voltage (input 3.5-28V with arbitrary value, output 1.25-26V with arbitrary value) Step-down Mode: Input / Output current (max.): 3A, rated input/output: 1A (Please add cooling fin when working in big current) This step-up step-down module with voltage display screen, you can see the input and output voltage Voltage regulating mode: (Step-up) Potentiometer rotates in clockwise, (Step-down) Potentiometer rotates in anticlockwise Note: Because of lower switching frequency and input high current, it is normal to use if it has some noise Quantity: 1pc