Yeahhh it may be the Whiskey ((Don't drink and derive folks)) but I seriously think that statement is wrong.

You cannot have 5mw over the entire course of its lifetime... milliwatts is a *rate*... not a quantity. 1/1000th of a Joule per second. It makes no sense to be the output of an integral over its life...

Even still... each microwave's lifespan is different... so a cheap chinese brand that is leaky as hell but dies after a week of use would be acceptable? ... Yeah that doesn't make sense at all.