The 'Classic' lamp hood currently only extends to 23cm, you can get that height up to 35cm by following this link.
www.aerogarden.org.uk/forum/2008/05/20/aerogarden-extending-the-height-of-the-lamps/
I thought I had seen it too, had a search but couldn't find it. Decided to post this after the failed search - will probably come across it now!
Oh - I put it here amidst my pepper growlogs... Would have made more sense in Lore / Hardware, huh.
Ah, well, you put it in a good place. 
Thanks gisette, I knew it was somewhere; just could not find it. 
Peat, this is just what I needed, so I'm bumping it up for others to see.
Thank you!
Not a problem TeaLover, it's helped me a number of times with the larger type grows.
Welcome by the way, I hope you enjoy the browse through the site. 
Thanks for posting that, Peat! I thought I had that somewhere around here, but I guess not!
The extending-beyond worked very well with my pro100, and saved me another doomed round of pruning!