2XFor DeWalt 20V 20 Volt Max XR 6.0AH Lithium Ion Battery Pack DCB204-2 DCB206-2
They performed as I hoped.
I bought the 2 battery pack, 1 charged easily, and one I needed to slide into the charger a few times in order for it to start charging. Time will tell but so far I'm pleased with the performance. I use them a lot.