Amazon.com: Made for Amazon Battery Base, in Black for Echo Dot (4th generation) Not compatible with previous generations of Echo or Echo Dot (1st Gen, 2nd Gen, or 3rd Gen). : Everything
Amazon.com: ANSMANN 9V Rechargeable Batteries 300mAh pre-Charged Low Self-Discharge NiMH 9 Volt Battery 9V Battery (2-Pack) : Health & Household