Bumpers, simply put, are training dummies for retrievers. They range from 8"-12" long and 2"-4" in diameter, can be plastic or canvas, and come in white, orange, grey, black, and cammo color. They float and they're pretty indestructable. The plastic ones have raised nobbies so the dog can grip it in his mouth. A short length of rope is tied through the hole at one end so the trainer can fling it a long way. Basically, bumpers take the place of the birds the retrievers retrieve, for ease of training. Letting instincts totally take over, any good retriever goes nuts over bumpers. Just crazy. They will go to any length to get the bumper and simply bring it back. You know how Border collies are crazy about sheep? Well, same thing. There's no separating a retriever from his favorite bumper. Tucker's favorite bumper is his orange one with the end chewed off. Too fun.