Holds 3 AA batteries in a series circuit. If you're using regular AAs that gives you 4.5V. If you're using rechargeable batteries that'll give you 3.8V.
Also features 6 inch leads as well as a red ribbon for easy battery removal.
This nifty little battery pack is perfect for any sewing project due to the sew through holes on each side. It works with a standard CR2032 3V battery, which is just what you'd want for lighting up LEDs.