Input: DC 3 V to 40 V (input voltage must be 1.5 V higher than the output voltage, no boost) Output: DC 1.5 V to 35 V voltage is continuously adjustable, maximum output current is 3 A Features: use SANYO solid-state capacitors, 36 u thickening circuit boards, high-Q inductance with LED indicator output Quantity: 6 pieces Size: 43x21x14mm Steps: connect to power source, adjust the swirl button on the blue potentiometer and monitor voltage with multimeter to get the needed voltage (The factory have tested these at max voltage so they are very high by default, takes about 15-20 turns CCW before the voltage starts ramping down) Notes: The input and output interface can not be reversed. Keep it under 2.5 A and use the heat sink when working for long hours. colour:blue Material:ABS Package Contents: 6 x LM2596 Power Supply Step Down Module Only the above package content, other products are not included. Note: Light reflection 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.