What's the deal with these Klon pedals?

[rupe]

Joe Perry was using one...not sure if he still is or not.

 

[petejt]

James Hetfield uses one too

I think it was just for his solo in Suicide & Redemption. For years now he uses a Line6 DM4 Distortion modellor in his live rig. He still uses it because I saw it last Saturday.