Fangrui Product Details Driver Current Regulation: Verf Measures The Voltage Of Gnd And Potentiometer Middle. Please Do Not Connect The Motors When Measuring The Voltage, Or Its Easy To Burn The Drive. Please Connect The Power Supply When Measuring Voltage As Well, Do Not Connect Only The Usb Power. Please Pay Special Attention To The Direction, Do Not Insert Wrongly! Driver Current Algorithm: I=vref Default I=1.25a Parameter: Default Current:1.25a Max Current:2.5a Logic Voltage:3.3v/5v Input Voltage:5.5v-28v Microstep:up To 1/256 Mode:dir/step,uart Colour: Blue + Black Material: Metal Package Contents: 1 * Mks Tmc2209 Stepper Drivers 1 * Big Heatsink 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.