Need a battery for your Arduino that is high enough to regulate the voltage to down to a solid 5V? Well here comes the 9V Snap to 2.1mm Barrel Plug Cable to your rescue! It allows you to plug in 9V and 7.2V rechargeable batteries to anything with a 2.1mm Barrel jack on it.
The 9V snap to 2.1mm barrel Plug cable is great for split supply operation when your running a motor driver, just power your microcontroller with this cable while and motor driver with another battery. This cable quickly clips onto our 3AA Battery holder, or 9V Alkalines, or 7.2V NiMH & NiCd rechargeables. It's perfect for powering Arduinos & Freeduinos or using with a 2.1mm Jack with switch. The tip is positive on 2.1mm plug side and the wire portion is 13.5cm long.