So, one of the types of yo-yo's that you're going to hear a lot of talk about, usually when you go, when your friends see a yo-yo and they were like, "Oh, I used to have a yo-yo," they're probably going to be talking about the brain. The yo-yo with a brain, also known as a clutch mechanism, is a very common type of yo-yo. And I just want to talk about it real quick because yo-yo's have changed a lot. And a lot of people think that a yo-yo with a brain is going to be the best yo-yo for them, but in fact, they're a lot different. There's a lot of limitations to them. I just want to talk about how they work, basically. So a yo-yo with a brain is shaped like a normal yo-yo. It goes up and down. It can still sleep at the end of the string with a good, strong throw, and it will still come back to yourself. But the key to this is that in the yo-yo itself, I'm going to open it up and give you guys a look inside here. What happens is you've got these two little plastic parts and springs on either side, you'll notice there's little ball bearings on either side. This is for weight. And what happens is as the yo-yo spins, these actually go towards the edge of the yo-yo away from the axle. And then as the yo-yo slows down, you'll notice there is this big axle in here. They actually clamp down on it and completely stop it from spinning. And that's what returns the yo-yo back to your hand. So as the yo-yo's spinning, these spread apart. As it slows down, they slowly come back together and eventually they clamp right down this axle. It stops the yo-yo completely from spinning, shoots it right back to your hand in the middle of a trick. The reason these aren't quite as good for the tricks that we're working on is because they sleep for a very limited amount of time. Since that the axle is going to get gripped, it's going to pull it back to your hand. You're going to be halfway through Rock the Baby and the yo-yo's going to shoot back to your hand on there and there's really not too much you can do about it. So it's great for learning the basics. But halfway through this, it's going to come back, shoot back to your hands. It's not going to work for you. So I highly recommend them if you just want to go up and down with the yo-yo. But if you want to start learning more advanced tricks without the yo-yo shooting back to your hands like that, it might be better to check out some of the ball bearing yo-yo's we're going to talk about in a minute.