I have had a tool box on my truck for 17 years and never had anything rust. First one for 16 years was a DeeZee aluminum box red label. New one is a Pro Tech and while I do not have any long term evidence yet on the new one I know it doesn't leak, so far anyway. I live in Colorado so it is fairly dry humidity wise. I have heard of people saying that theirs doesn't leak yet it still gets wet inside, condensation perhaps from too good of a seal. In which case a couple holes drilled in the bottom of the box should take care of that. I know my new Pro Tech is certainly sealed much better than the DeeZee was so I am keeping an eye in it but so far have not noticed any issues with condensation.