Has fcc and ce certification that they are made from environmentally friendly production technology and materials, made function,voltage, current testing before packaging. This allows the Leonardo to appear to a connected computer as a mouse and keyboard. The Leonardo differs from other boards using separate USB-Serial chip in that the ATmega32u4 has built-in USB communication, eliminating the need for a secondary processor. The keyestudio Leonardo is a microcontroller board based on the ATmega32u4,It has 20 digital input/output pins (of which 7 can be used as PWM outputs), 12 analog inputs, a 16 MHz crystal oscillator, a micro USB connection, a power jack, an ICSP header, and a reset button. Please NOTE: Open the Arduino IDE, you’ll need to click the “Tools”, then select the Board that corresponds to your Arduino. If you don't choose the correct development board type, it will cause the compilation to fail to transfer. So this is a place that needs special attention.