Thickness gauges with PP3 battery

 

— batteries of a characteristic rectangular shape, with a pair of contacts on one of the ends. They have a nominal voltage of 9 V. They can be made rechargeable, but for a number of reasons this option has not received distribution, disposable "Kronas" are used much more often.

The advantage of all replaceable batteries (compared to built-in batteries) is the ability to quickly replace a dead battery with a fresh one. On the other hand, such power supplies have to be purchased separately, and then regularly spent on fresh batteries.