1. This Module Is An Adjustable Step-Down Module 2. The Output Voltage Can Be Changed By Adjusting The Blue Adjustable Resistor On The Module. 3. The Input And Output Voltage Difference Is 1V, And The Minimum Output Voltage Is 0.8V. 4. The IN- (Input Negative), IN+ (Input Positive), Out- (Output Negative), And OUT+ (Output Positive) Marked On The Module Must Be Connected Correctly, Otherwise The Module May Be . 5. Need A Professional To Install The Corresponding Accessories To Avoid Damage To The Accessories. Led Constant Current Driver Usage: 1. Determine The Operating Current And Maximum Operating Voltage You Need To Drive The Led; 2. Adjust The Constant Voltage Potentiometer To Adjust The Output Voltage To About 5V. 3. Use A Multimeter With A 10a Current Block To Measure The Output Short-Circuit Current, And Adjust The Constant Current Potentiometer To Make The Output Current Reach The Predetermined Led Operating Current; 4. Adjust The Constant Voltage Potentiometer To Make The Output Voltage Reach The Maximum Working Voltage Of The Led; 5. Connect The Led And Test The Machine. (Steps 1, 2, 3, And 4 Connect The Module Input To Power, And The Output Is Unloaded And Does Not Connect To The Led Light.) Material: PCB colour: As shown Package Contents: 4 x Lithium Battery Charging 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.