MegaPulse Butterfly Loop PEMF Applicator works with any MegaPulse Device. The butterfly design targets high-intensity PEMF between the two coils and can increase the power by more than double. This works great for extremities such as legs or arms and can also be used flat. The flexible usage makes the butterfly loop a great add-on to anr Megapulse System. Electromeds offers FREE shipping with this item.