Abstract: An apparatus for use with a radio frequency generator and an indifferent electrode to treat tissue in a mammalian body includes a needle having a distal portion and being adapted for coupling to the radio frequency generator and a layer of insulating material extending around the needle but exposing a part of the distal portion of the needle. The exposed part of the needle is sized as a function of the thicknesses of the plurality of layers of tissue to facilitate placement of the distal portion of the needle in the plurality of layers by measuring impedance between the needle and the indifferent electrode.