DONíT BUY A SIREN UNLESS YOU KNOW WHAT YOUR DOING!
Does that sound brash? We see this so many times in the industry and there are some real pitfalls that need to be avoided. I hate to say this but "Let the buyer beware" is a saying that can apply if your not careful. This is an unregulated industry and we are not tied to any requirements except those YOU create.
The worse thing you can do is to let some vendor guide your bidding process. When a vendor guides a bid we see a bid that defines a product rather than a requirement. We see bids that are written to preclude competition from participating in the process.
What do you need? You need warning coverage, effective warning coverage. There are FEMA guidelines to help you understand sirens systems, how they work and how they project sound. You must at least know the basics if you want to be protected.