Wikipedia
Changeables, also known as McRobots, was a toy series produced by the McDonald's corp. and given away with fast-food meals at their restaurants. The series used the then-popular " Transforming Robots" toy concept in conjunction with their own products. The robots could transform into items (mostly food) from the company.
There were three series (1987, 1989 and 1990) of McRobots.
The original series featured six food items that transformed into unnamed robots. The second series included re-colors of two Series 1 robots (Big Mac and Large Fries) and six new molds. Series 2 also gave the robots names. Series 3 had four molds from Series 2 and three from Series 1 but changed into dinosaurs instead of robots. It also had one new mold, the Happy Meal box.
Intended for use by small children, the Changeables line of toys was surprisingly sturdy as each figure was made from fairly thick plastic and typically contained only three moving parts. This made changing the individual figures from food item to robot/dinosaur and back fairly easy even for those within the intended age range.
There were also some under-3 (U-3) toys in the sets that did not transform.