3/4" I.D. preformed coil heats nuts up to 5/8" in deep areas up to 11". Heat and expand frozen, rusted, or thread-lock compound nuts with out the collateral damage from a flame. Uses high frequency magnetic fields to heat metal and only metal, induction heat. Operates on 120 volts/1000 watts of power!. Faster and safer than a torch Estimated 500 uses minimum. Heating a nut red hot will reduce the life of this coil.