Ultra high decibel, keep you in safe: Through measurement, it is determined that its decibel is more than 100, which is the volume that can really alert pedestrians and bring you safety.Integrated PP material hammer, rust proof and more stable: Integrated plastic hammer instead of rusty spring can prolong the product life and give you better cost performanceEasy installation: It can be installed by simply tightening the screws. It's easy to operate, even for children which make it really a good product that saveing time and effort!