They are some soft material on a post that go into your handlebar ends. You just push them in. The reason I tried them is because I saw a demonstration with a bare handlebar dropped on the floor without these, and it hit and bounced a few times. With the Buzz-Kills in, the bar just dropped, and stayed put. So I figured it was worth a try, and it was.They're not expensive either. I've got a big range of road surfaces here, too, so I'm looking forward to not tensing up over every bump. Oh, and supposedly George H. won a race last month over cobbblestones using them.