E Stim OMG Torpedo Electrode.
If you are looking for something truly massive, and are not prepared to compromise then OMG is the one for you.
OMG (it stands for 'Oh My God') was originally designed as a display piece, but more and more people wanted one, to the extend they are now part of E-Stim Systems product range. A massive 3" in diameter and weighing over 1.6Kg these are massive in every way. And of course they are fully functional BiPolar Insertable electrodes. The coin in the picture is a UK 50 pence.