Driver Current Regulation:Verf measures the voltage of Gnd and potentiometer middle. DO NOT connect the motors when measuring the voltage, or it's easy to burn . connect the power supply when measuring voltage as , do not connect only the USB power. pay attention to the direction, do not insert wrongly Driver Current Algorithm:I=Vref Default I=1.25AParameter:Default current:1.25aMax current:2.5a voltage:3.3v/5vInput voltage:5.5v-28vMicrostep:up to 1/256Mode:dir/step,uartColour: blue + blackMaterial: metalPackage Contents:1 * MKS TMC2209 Stepper Drivers1 * Big HeatsinkOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.