https://www.focal.com/en/headphones-0/headphones/for-home/celestee

Interesting. Been considering a closed back. 

With a 35Ω impedance and a 105dB/mW sensitivity they shouldn't be much harder to drive than a pair of Grado. They look comfortable like the rest of the Focal line, but they don't provide a figure nor explain the build for noise isolation. I'm guessing they're more concerned for the surrounds not listening to your music than vice versa.