The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x). It has more or less the same functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one.
The module (MicroSD Card Adapter) is a Micro SD card reader module, through the file system and the SPI interface driver, SCM system to complete the file to read and write MicroSD card. Arduino users can directly use the Arduino IDE comes with an SD card to complete the library card initialization and read
The A4988 is a complete Microstepping Motor Driver with built-in translator for easy operation. The driver has a maximum output capacity of 35 V and ± 2 A. It can operate bipolar stepper motors in full-, half-, quarter-, eighth-, and sixteenth-step modes.