It stops the bacteria that causes odour form growing.

I'm not an old lady, and I've never been to Mexico, but I've been using crystal rock deodorant for more than 25 years.

I started using it in school, and I remember it took a week or two to work properly (all teenage boys smell right?) but since then it's all I've needed.

It's cheap too, until you drop it on the tiles and smash it into tiny pieces... then you just collect all the larger chunks to keep using!