What do you mean? The T1 is Semi-Open like the DT 880.
If you're referring to the DT7/8/9 series the 770 is closed but the other 2 are open.
They've made a few closed cans meant for more portable use, but the only true 'high end' closed headphones (IMO) are Denon, Ultrasone (Ed. 8), and the Thunderpants.