I bought these headphones one year ago, because as a drummer, i was tired of using normal in ears with cheap earmuffs on top of them, so i could ear music and isolate the sound of my drum set.
These headphones do both, they isolate external sound, and they let you ear the band/mp3/etc you're playing with.
They are pretty similar to the Vic Firth ones, but they cost less than half the price. They also isolate a little less than the VF, but nothing special. They have a spiral cable, that when you stretch it, it's way bigger than the VF cable.
I also wear glasses, and they can be a little bit uncomfortable after using them for a while (+1h) because they are pretty tight. Tight headphones + glasses are not a good mix.
The sound itself isn't great, but it's good enough to do the job if you're not that picky.
Pros: really cheap, good isolation, long cable
Cons: the sound is not that great, a little uncomfortable after hours of use
Choosing between this and the Vic Firth ones will come down to your preference, do you prefer a cheap but reliable option, or a more expensive (2x) but a bit better option?