Features Use the interchangeable A4988 or DRV8825 compatible step driver. This is a set of disassembled parts, and you need basic soldering skills to solder them together. Compact design, stepper motor can connect four-pin plugs or be soldered. The expansion board can be used for engraving machine or 3D printer drivers. Compatible with GRBL 0.8. Open source firmware, convert the G-code command into a step 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 to adjust the firmware to perform the complete shaft 4). Specifications:CNC Expansion Card: Version: V3.0. Colour: red. Size: 68 x 53 x 18 mm/2.67 x 2.08 x 0.7 inches. Voltage: DC 12V to 36V (only the DRV8825 driver can handle up to 36V, so please consider the voltage for the power supply) 4 pieces A4988 driver: Colour: red. Size: 20 x 15 mm/0.78 x 0.59 inches. Thermal cut-off circuit: yes. Cross-current protection: yes. Ground fault protection: yes. Short circuit protection: yes. Compatible logic voltage: 3.3V and 5V Five level modes: full, 1/2, 1/4, 1/8 and 1/16 mix with slow current attenuation model. Internal UVLO and low RDS output (on). Automatic current attenuation mode detection/selection. Phase rectifier, low power consumption. Warning: Connecting or disconnecting the stepper motor when the driver is on may damage the driver. Pack of 4 heatsinks: size: 8 x 8 mm/0.31 x 0.31 inches. Colour: white. Package includes: 1 x V3 Expansion Board 4 x drivers. 4 x heat sinks. Package List