Rechargeable Standard Battery, 550mAh, NiMH 1.2V
From Amazon
Ansmann AAA DECT Phone Batteries [Pack of 2] Long Lasting Low Self Discharge Rechargeable AAA Type 550 mAh NiMH MaxE Pro Battery For DECT Cordless / Portable Phones
Conrad Electronic
Ansmann DECT maxE HR03 AAA battery (rechargeable) NiMH 550 mAh 1.2 V 2 pc(s)
OnBuy
AAA Ansmann Batteries Micro DECT 550 mAh (2 Pack)