Musicians Roadhouse

Can someone explain to me why the flat cabinet to the super100jh stack is taller than a normal one?

I've never seen hendrix use one like that so I'm a little confused about it and wondering what purpose it serves?

That's exactly the same as it was back in the day; -

http://www.youtube.com/watch?v=5lVU2NRC ... re=related

The SUPER100JH stack is from the 1966 to 67 period stacks Jimi was playing, not the later JMPs from 1968 onward.