Certainly they work, but he did not expect it to last over time.
Still, I'm pretty careful and the product never fell. Nevertheless, after 2 months of use, the spring is completely twisted and the product unusable.
The room to slide the batteries being just large enough to insert the battery, it is not just my doing, but in my opinion a rather poor quality.
By 2 or 3 extra, you will find products not only more powerful, but mostly better designed and more robust definition.
