1. As an expansion board, Base Shield v2 has many Grove connection interfaces, so that you can use multiple Grove products together. It is compatible with a range of for products. 2. Power supply compatibility: Each Grove connector has four wires, one of which is Vcc. However, not every microcontroller motherboard requires a 5V supply voltage, some require 3.3V. That's why we a dded a power switch on Base Shield v2. In this way, you can adjust the voltage of Vcc through this switch to that the voltage of Vcc is the same as the power supply of the motherboard. 3. When using for and Base Shield v2, please turn the switch to the 5v position; when using for Seeeduino Arch with Base Shield v2, please turn the switch to 3.3v. 4. The development board is compatible: the number of pins is the same as for R3. Color:Black & White Material:Plastic Package Contents: 1 * sensor expansion board 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.