The 9V Battery to 5.5/2.1 Connector (for Arduino) is an adapter that allows the connection of a 9V battery to devices such as Arduino, using a common 5.5mm/2.1mm DC plug. This connection is typically used to power the Arduino or other devices with suitable voltage from a portable battery. The adapter features a central male terminal of 5.5mm and a diameter of 2.1mm, which is compatible with the majority of Arduino boards and other microcontrollers. In this way, you can have a simple and convenient solution for powering the Arduino in projects where mobility and portability are important.