Yes, real deer antlers. Deer shed these annually so it's not necessary for them to die in the process. My boy doesn't care about them yet, but he may grow into it. I should have mentioned earlier, he only goes for the "odorless" bully sticks. If I buy low odor he ignores them. It has to do with how they are hung when cooking, and how much fluid is allowed to drain out. They are, in fact, bull penises as mentioned before. I highly recommend the long braided ones. I've found them for as low as $5 a piece, which is expensive, but an 18 inch braided one will last much longer and is basically like 3 long singles wrapped together. I sometimes alternate the bully sticks out to allow older ones to dry for a few days, seems to make them last longer. Definitely do NOT leave your dog unattended though, since any chew can be a choking hazard. I made the mistake of leaving one in my dogs crate. I saw him go to sleep and figured he was out for the night. When I woke in the morning the entire bully stick was gone, which gave me a pretty good scare. He was fine, but it was a bad idea.
I have read that deer antlers are pretty safe since they can only chip tiny pieces off at a time, since they're so hard. Since they're basically nothing more then Calcium the dogs can handle the small pieces.