I'm not sure why people want to pull out different adjectives except to make their product seem unique from the crowd, or define line differences. I'm getting very fatigued from the word "extreme". Corn chips, soft drinks, and wild sports couldn't do it--but a good background check has.
Only the actual weight and construction make it a stronger box.
Put my 800# box on a 100hp unit--"light duty"; put the same one behind a 17hp tractor--"extreme duty"
Words like heavy, super, and extreme aren't a lot more helpful than wonderful, fantastic, or really, really good except to categorize products within a manufacturing line.
Have an extremely good day!