The rather squat proportions of Energon Optimus Prime start to make more sense when you realize he's best represented as the centerpiece of a combiner. Prime in his vehicular mode hauls a trailer that carries four additional vehicular drones, labeled on their chassis as OP-1, OP-2, OP-3 and OP-4. OP-1 is Fire-1, a firetruck. OP-2 is Copter-2, a helicopter. OP-3 is Digger-3, a treaded drill tank. And OP-4 is Submarine-4, a submersible. These become the limbs that attach to the core body of Optimus Prime, becoming a super-sized figure. The drone limbs are interchangeable, meaning each can become an arm or a leg. These attachments activate electronic light and sound features in the core body.
