iFixIt replacement battery quality better than ebay?

FYI, I purchased an iPhone 4 battery from iFixit back in Aug 2011. It was a dud. When it fully died, I plugged it in and it said it was charging but it never did.

They sent a replacement and this time, I had left the phone alone for probably a week because I wasn't using it due to some family issues. When I picked it up after a week, (not to scare you) the battery had swelled inside the iphone and pushed the back panel out a little. Thankfully it didn't cause any damage to the phone or the back panel. I requested a replacement battery again. They sent one and again, same problem as the first -- it wouldn't charge. Again, I requested a replacement and that time the battery was fine and it's been used perfect since.

I would be interested to know if these are OEM batteries that maybe couldn't be fully certified for one reason or another OR if they are in fact 3rd party batteries because they look IDENTICAL to the original battery. If anyone knows if the iphone 4 batteries that iFixit sells are OEM, please post.

All in all, aside from the fact that I had to get 3 RMA's, the final battery worked great and the customer service was great as well. I've ordered from ifixit a few times before and it's always been a good experience