Features 1、Use removable A4988 or DRV8825 compatible stepping driver 2、The extension board can be used for engraving machine or 3D printer driver 3、Compatible with GRBL 0.8. Open‑source firmware , converting G code command into stepping signal 4、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) 5、Compact design, stepping motor can connect 4 pin connectors or be soldered Specification Features: Use removable A4988 or DRV8825 compatible stepping driver. The extension board can be used for engraving machine or 3D printer driver. Compatible with GRBL 0.8. Open-source firmware, converting G code command into stepping signal. 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). Compact design, stepping motor can connect 4 pin connectors or be soldered. This is a set of disassembled part, and you need basic soldering skills to solder them together. Specifications: CNC Expansion Board: Version: V3.0 Color: Red Size: 68 x 53 x 18mm / 2.67 x 2.08 x 0.7" 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 Five Step Modes: Full, 1/2, 1/4, 1/8 and 1/16 Mix 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