Features: Open circuit diagram of the original design, the development of software interface for free download, can also be in accordance with the requirements and their modified, download the program is simple and convenient. Can simply use sensors, all kinds of electronic components connection (such as: LED lights, buzzer, buttons, photoresistance, etc.), make all sorts of interesting work. Microprocessor controller, using high-speed development interface and the environment are very simple and easy to understand, very suitable for beginners to learn. Specification: 100% Brand New! Digital I/O Digital inputs/outputs were：0~13. Analog I/O Analog input/output: 0~5 Support ISP download function. The input voltage: when connected to the computer USB without external power supply, external power supply 7 v to 12 v dc input voltage. Output voltage: 3.3 V and 5 V dc voltage output dc voltage output. Package Included: 1 x UNO R3 Board 1 x USB Cable NOTE: The size is just for reference, there maybe exist a measurement error, please check carefully before you buy it. Color may vary slightly due to different calibration of each monitor.