Ours is custom built, I cant give any details of it or its opperation but lets just say its trick..
For comcerial zappers, I have nevere tested any of them but have heard good things about the quillen.. I can't remember who, but a while ago another matcher was telling me that he was using that one with decent results.
I don't know about the indy one.
Sorry wish I could help more.
Korgae