Hah, hah, hah! There was nothing "bulletproof" about them. I went through at least 3 "bulletproof" PDP3s in about 6 months. They were utter pieces of crap. One time, the rheostat knob came off in my hand when I went to turn it on, my first time using it, just purchased "bullet proofed". Worst of all, the person who "bulletproofed" them, (Ross Dean, IIRC) flat-out refused to warranty/stand behind his work, but would be more than happy to fix them for a price.