Size Name:4 AA DC - 1 pc 4.5 volt power supply when you use 1.5v AA batteries. Case to protect batteries. On/off power switch. An On/Off switch lets you control the power right at the source without unplugging. Batteries not included. Perfect for portable Arduinos, motors, solenoids, LED strips, etc. An On/Off switch lets you control the power right at the source without unplugging.