Thanks in large part to the ... alternate mode and the real truck. Incidentally, there's a somewhat popular secondary theory ...

Though this might fit better with the Beast Wars Maximal Optimus Primal, the toy splits open through a lever to transform ...

We wouldn't be surprised to see this 2-in-1 build--Optimus ... mech and truck modes--sell out again soon. If Amazon sells out, it's worth noting that the Lego Store restocked Optimus Prime ...