Dimensions:
Intruder - 105mm (4.1") length by 50 mm (2") diameter
Invader - 120mm (4.7") length by 60mm (2.35") diameter
Intimidator - 135mm (5.3") length by 70mm (2.75") diameter

All ElectraStim accessories come with a "Pin Connection"... so if you have wires from any of the Erostek or Folsom boxes that have the standard "Banana Plugs" at the end of your wires... you'll need to have a set of the adapters called "Banana to Pin"