Silver Oxide (SR) and Alkaline batteries (LR) are commonly used in watches, clocks, timers, calculators, laser pointers, toys, and LED "blinkies". Batteries that meet the IEC 60086-3 standards for watch batteries carry a "W" suffix. The functional differences between silver oxide and alkaline are:
The most common name for this battery is SR66. However, it is also called AG4, SG4, LR66, 177, 376, 377, and SR626SW. All have dimensions of 6.8 mm diameter and 2.6 mm height. Alkaline varieties have mAh from 12-18 and the silver oxide varieties have mAh of 26.