The Duracell PX28L battery is commonly used in cameras & attachable camera flashes amongst other uses. It benefits from a 10 year shelf life & is therefore suitable for holding a spare in stock. The PX28L battery can be used as a replacement for existing 4LR44 & 4SR44 batteries. PX28L batteries are mercury free & will replace banned Mercury Oxide PX28. You can be assured of the high quality & manufacturing process trusted with Duracell batteries.