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This is a Moonracer head. It is intended for figures with a 4mm ball joint, such as Combiner Wars Streetwise and many other deluxe sized figures. If in doubt, just ask me in the comments and I can try it out for you to see if it fits. For FOC Sideswipe/Jazz, you need my ball joint: http://shpws.me/MWrU.
If you would like this head for a different body mold, feel free to make requests!