OctagonStar DRV8825 Stepper Motor Driver Module 4-layer for 3D Printer Reprap RP A4988(5PCS) DRV8825 Stepper Motor Driver Module. 4-layer,Improved heat dissipation,Simple step and direction control interface. Six different step resolutions: full-step, half-step, 1/4-step, 1/8-step, 1/16-step, and 1/32-step. Adjustable current control lets you set the maximum current output with a potentiometer, which lets you use voltages above your stepper motor's rated voltage to achieve higher. Brand Listing, If you buy is not OctagonStar brand product, You Can Apply for a Refund and Compensation.