Together with additional tools (Uhrenöffner, plastic tweezers, mini screwdriver) can be a watch battery change in an instant. Cost point 1.70 EUR for the battery, compared to 10 EUR in watchmaking. After 3 mix-ups thus the entire tool paid for itself. The quality of the closer is perfectly adequate for 1-2 cycles per year and household. Continuous use in the workshop, it will hardly survive.