Apple Watch (38 mm, Original & Series 1) Battery
Replace a 205 mAh battery compatible with Apple Watch 38 mm Original and Series 1 Models A1553 and A1802. 3.8 Volts (V). Battery Model A1578.
Apple Watch (42 mm, Original & Series 1) Battery
Replace a 245 mAh battery compatible with 42 mm Original or Series 1 Apple Watch models A1554 and A1803. 3.78 Volts (V). Battery model A1579.