Redz are the only makers I've seen who do different sizes.
Tho others like Mantis and that, are made totally of elastic with velcro on the end, & I think that would fit from S to XXL
NXe 3+2+2 i have to say is the best pack i have worn, its mostly personal preferance with how you like it to fit and the design of it, but for me its got to be NXe as i love its fit an think they are such a simple design its real hard to go wrong!