No its not. Check the link. I spent 2 years objectively testing deadeners with a calibrated measurement microphone.

If your interested, and have time, I’d like to discuss deadening a little more in depth. Don’t take this the wrong way, as I’m not here to bash. However, I spent 2 years objectively testing damping materials of all sorts, including gtmat, and feel I am uniquely qualified to explain some things.