Why is this little hole underneath the locks? If you know the reason, then your lock will not be bad

The barrel near the key to the bottom of the lambermoon is to provide a space to put oil in locks, so that the time passes with passage of locksmith etc. In case of locks use under surface water, this hole also works as a filter.
In the upper end of the hair booth pan, there is also a barrel hole, whose goal is that if a child swallows her by mistake, her breath will be restored through the hole. The holes made on the end of the scale to hang it, so that you are safe when you are not using it.