Pair of flappers came crammed in cardboard box that was really only sized for one. Probably why 1/2 was warped a bit around the lip. Soaked it a bowl of hot water for a few min and while still a bit uneven it's been sealing fine with the weight of the water on it. Checked both flappers, shutting water off each night and finding tanks still full in the morning. So quality is a bit lacking but so far hasn't affected their function. Old plastic flapper wasn't leaking but our toilets are all newer high efficiency 1.28gal/f standard. Trying different types since old flapper would close too quickly which didn't allow bowl to fill up to proper level. Still not perfect but these do seem to stay open a hair longer, extending the fill valve's run time to fill both the tank and bowl.