RPMs = Robot Powered Machines. Found these at an endcap at WalMart today, have not seen these yet. They were $3.46 each or close to it. Great price, only downside is they plastic, not diecast, but given what they are, this is easily overlooked. They are Matchbox/Hot Wheels size cars with nicely. painted Robot's (and name print) underneath. pick some of these up, they are so cool, and fairly priced IMO.