Canadian Tire is a retail chain which operates only in Canada. They're probably one of the biggest retailers of hardware and tools in the country.
One of their store brands is Mastercraft. About ten years ago, they carried a small dark-gray "Mastercraft Pocket Digital Multimeter". The model number is 52-0051-4. It cost between CAD $10 and CAD $40 or so, depending whether or not you bought it on sale.
The multimeter uses one battery. When the battery gets low, the multimeter starts giving you inaccurate readings. To replace the battery, you unscrew two screws and open the multimeter up.
Engraved on the inside of the multimeter's battery holder is a generic battery symbol, a plus sign, and a minus sign. This engraving tells you which way the battery goes. Unfortunately, there's no information printed or engraved anywhere on the outside or inside of the multimeter about which type of battery it requires. So, what type of battery does it require?