This head is to convert animated shadow blade leader class Megatron into animated The Fallen.
Installing the head requires disassembly of the torso. Due to the electronics and their integration into the original figure, either the full board will need removing, the LED for the head will need cutting off or a component of the old head will need to be cut to safely remove the wires. Otherwise, the head fits into the exact space left by the original head and fits comfortably into the cockpit for transformation. Be careful of the flame tips. There is enough clearance to not have parts clash, but it is easy to accidentally catch them.
There is a second optional part to this conversion, however it is quite expensive on Shapeways. It is a fix for the original figure's unfortunate knees. If you have your own printer and would prefer to print the files at home they can be found here https://www.etsy.com/uk/listing/824307087/transformers-animated-the-fallen?ref=listings_manager_grid