There has been some dicsussion on these, I am not 100 percent sure, I have quite a few in different sizes, 3" 6" and 8" that I know are real and all of them even the 3" says Reg. U.S. Pat. Off. around the bottom. I have never seen a 3" repo'd so that helps some as a few of mine came off pumps from the ranch so I know their history. I have always been suspect of the ones that say made in usa or say nothing at all at the bottom. I see them on ebay that say guaranteed original but we all know that mean nothing. I just looked at mine and all but one have a black back, most with rack lines, the odd 3" has a white back with identicle rack lines. Personally if it said made in usa I would stay away, if anybody has any other info I would like to hear it because I have passed on a lot of them over the years because of this thinking. hope this helps..Frank