This is a simple 6 cell AA battery holder. The 5 inch cable is terminated with a standard 5.5x2.1mm, center positive barrel jack connector.
The connector mates with the barrel jack on the Arduino (among a number of other products) allowing you to easily make your project battery powered.
Material: Hard Plastic
Used for 6 X AA batteries or rechargeable batteries, ordinary battery output 9V voltage, rechargeable battery output 7.2V voltage
1x 6 x AA Battery Holder with DC Barrel Jack Connector for Arduino(2-Seitig)