Panasonic LR-44 battery. Price is for 2 pieces of the battery.
The LR-44 battery (also known as G13A, 357A, A76) is commonly used in compact cameras/small electronics.
Specifications:
Voltage: 1.5 V
Size: 11.6 x 5.4 mm
Chemistry: Alkaline Battery
Mercury-free (0%Hg)