John and Andrew Doney invented a device for balancing rotors. Although they registered their invention with the U.S. Patent and Trademark Office, it was never put on the market as an automobile wheel balancer. Some time later, Exetron Corp. produced an automobile wheel balancer that used a device similar to that of the Doneys. Given the fact that the Doneys had not put the patented product in commerce, does Exetron's use of a similar device infringe on the Doneys' patent? Explain your answer.