try again, the patent was filed in 2002 and has a 20 year utility patent, you won't see any non DUI zip seals in this country for the better part of the next decade. They also have an EP so it's valid in most of the EU, a few countries there don't acknowledge it which is why there are some knockoffs, but it is highly illegal to bring them into the US and most of the EU, so whether you care about them getting imported or not, if you knowingly buy them and have them shipped here you are violating Federal Laws, as is the company doing it, and since DUI is now under the German GBH group, I wouldn't really want to risk it, they are big enough to sue you just for ****s and giggles, and as a guy running a small niche business I think you'd be pretty pissed if you patented something on your DPV's and some guy went and tried to knock you off and people were knowingly buying that product knowing full well it was violating your patent just to save a few bucks....
DUI will put zip seals on non DUI suits I believe. It would be stupid of them not to since they make so much money on the new seals. May as well just have rings installed, better off doing that anyway, cheaper, more versatile, less hassle.