When I look at O-rings I look at two things. First, they work. And these rings work fine on my HD Fatboy. Second, what is the expiry date? Unless you have 4 or 5 Harleys in your garage, changing 10 oils would take several years. Some rubber-based products can deteriorate and become brittle just by sitting on the shelf. But if I keep them dry and out of the sun I can use at least half of it. In that time I save 10x more than buying them, you know where.