Operating Voltage:5V Input Voltage (recommended):7-12V Input Voltage (limits):6-20V Digital I/O Pins:54 (of which 15 provide PWM output) Analog Input Pins:16 DC Current per I/O Pin:40 mA DC Current for 3.3V Pin:50 mA Flash Memory:256 KB of which 8 KB used by bootloader :8 KB EEPROM:4 KB Clock Speed:16 MHz Due to different factory batches, the product words are different, and the product accessories have slight differences in color and appearance, but it does not affect normal use Colour:P o Color Material:PCB Package Contents: 1 x R3 improved version development board 1 x USB charging cable 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.