This is a big button which gives the first touch of the physical world. Simply plug to IO expansion board to finish your first taste of Arduino. Features: 1. Wide voltage range from 3.3V to 5V; 2. Standard assembling structure (two 3mm diameter holes with multiple of 5mm as distance from center); 3. Easily recognitive interfaces of sensors ("A" for analog and "D" for digital); 4. Icons to simplely illustrate sensor function; 5. High quality connector; 6. Immersion gold surface. Specification: 1. Supply Voltage: 3.3V to 5V; 2. Easy to 'plug and play'; 3. Large button keypad and high-quality first-class hat; 4. Able to achieve very interesting and an interactive work; 5. Interface: Digital; 6. Size: 22 x 30mm.