Button Cell Battery, 125mAh, Alkaline
From Amazon
VARTA Batteries Electronics V13GA Alkaline button cell battery 2-pack, Button cells in original blister pack of 2
Conrad Electronic
Varta Button cell LR44 1.5 V 2 pc(s) 155 mAh Alkali-manganese ALKALINE Spec. V13GA/LR44 Bli2