Question for the ladies - hair brush

[Mondo]

I am late getting a friend a birthday present, last year I got her some GHD's so it's a bit hard to top it therefore i am going to get a one of these brush to compliment it. But i dunno which one to get....

She has long hair and light them straight, what size brush is best. I can show you a pic of her hair if it helps but length wise it goes down to just under her shoulders.

http://www.beautysleuth.co.uk/bin/ve...n&setpagenum=2