those are known as "candy box toys" in japan. For $4, you'd buy the box and not know what you'd have in there. You randomly buy packs trying to collect a set ... just like baseball cards.

The original six builder was an autobot. Then, 2 out of every 12 boxes contained a "chase" (aka rare) color variant. These figures were either green or metallic charcoal grey.

The US KayBee Micromaster Devastator is the "chase" (aka special) edition version. Hasbro took all the green guys and prettied them up in better packaging.