Vic Firth SIH2 Sound-Isolating Headphones
The sound quality is far better than expected from a low cost closed back headphone, and it's ideal for monitoring quiet microphone recordings while avoiding feedback. I wouldn't class them as true HiFi headphones, but they are not intended to be.
The sound isolation is excellent, and similar to most ear defenders.
They are light and comfortable, despite having the fairly high clamping force that is required for good isolation.
I'd recommend them to anyone wanting isolating phones, but the adjusters need some attention.