K2 3.2v 41ah Lifepo4 - Shelf J1
If you are in the car audio world these are beast batteries. Check the data sheet, they can pulse 2400 amps. That is 60c discharge for 2 seconds. Or almost 17c (675a) continuous. Other sites have these new for around $260 but we have 8 in stock at just $60 each. They are used but have been tested and are testing over 85% capacity. They came out of a military application.
Spec sheet is in the 2nd photo. I wish we had more.