I've had these two little guys for along time. They seem to match U-559 or U-560. Though very similar there is a quality difference. The one on the right is more crude and looks older. There is a listing for a NN Imperial in white but not for a Thomas in white. If they're both Imperials, they weren't made real close together in time. I'd always assumed the one on the right was Imperial and the one on the left was Thomas.