This is to prevent backlash when changing bait or hooks. It weighs approximately 0.8g. I've used it for about 3 seasons, and I don't recall any major problems. The screws are made of polycarbonate and won't rust. The rubber used for the stopper is also used in factory machinery and outdoor construction, so it's quite durable. Please consider it as a simple stopper. *The reel itself is not included.*