The Feniex Hammer Low-Frequency 100-Watt Siren is the perfect add-on for your current siren system! The Hammer produces a low-frequency tone that shakes the ground and alerts other drivers that you're approaching. You can create even more power by adding two Feniex Hammers to your set up, creating a 200-Watt earth rumbling alert. The Hammer is designed to alert drivers ahead of you or when approaching an intersection. It is intended to supplement your current siren system, not replace it.