Neat blog writeup on the various 3rd party Transformer 'headmasters'. They were part of the Japanese TF cartoon, but I grew up with the toys: Tiny robot heads that detached, and turned into smaller robots. Sort of a 2-step Russian-doll thing, but with robots. :)
https://tilallaremine.wordpress.com/2011/04/28/jb-01-and-jb-02/
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