Features PWM spindle and direction pin, 4 shaft support (X, Y, Z, A ‑ you can copy X, Y, Z or use pin D12 and D13 customize firmware perform complete shaft 4) Compatible with GRBL 0.8. Open‑source firmware , converting G code command into stepping signal The extension board can be used for engraving machine or 3D printer driver Use removable A4988 or DRV8825 compatible stepping driver Compact design, stepping motor can connect 4 pin connectors or be soldered Specifications:CNC Expansion Board: Version: V3.0 Color: Red Size: 68 x 53 x 18mm / 2.67 x 2.08 x 0.7" Voltage: DC 12V to 36V (only DRV8825 driver can handle up to 36V, so please consider voltage for power supply) 4pcs A4988 Driver: Color: Red Size: 20 x 15mm / 0.78 x 0.59" Thermal Shutdown Circuit: Yes Cross Current Protection: Yes Ground Fault Protection: Yes Short Circuit Protection: Yes Compatible Logic Voltage: 3.3V and 5V Five Step Modes: Full, 1/2, 1/4, 1/8 and 1/16Mix with slow current attenuation model. Internal UVLO and low RDS (on) output. Automatic current attenuation mode Detection/Select. Phase-in rectifier, low power consumption. Warning: Connecting or disconnecting stepping motor while driver is powered on might damage driver. 4pcs Heat Sinks: Size: 8 x 8mm / 0.31 x 0.31" Color: White Package Includes: 1 x V3 Extension Board 4 x Drivers 4 x Heat Sinks Package List