GutAlkaLi LR44 Battery Pack of 20 – 1.5V AG13 Batteries for Watches, Hearing Aids, Glucometer, Key Fobs and Small Electronics – Silver Oxide Chemistry Provides Stable Voltage and Long Lifespan: Amazon.co.uk: Electronics
Amazon.com: Tenergy 1.5 Volt Battery LR44, Button Cell LR44, ag13/LR44 Batteries Equivalent, Ideal for Watches, Laser Pointers, Small Toys, Portable Electronics, and More, 20 Pack : Health & Household