WWII Air Raid Siren

This is what I believe to be a World War II air raid siren from a Nebraska Ordnance plant where they made bombs along with many other materials. When I think of the people working in the ordnance plants I think of the Rosie the Riveter posters! I believe the brand is Federal Electric but it is missing the label as you can see it has an original metal tag from the Nebr. ordnance plant & is numbered. Why would they remove the original label with Federal Electric on it? I have not seen any sirens with this tag. My husband put a plug on it because it did not have one and it works great! He has had it for over 30+ years & he knows that it came directly from one of 2 ordnance plants in Nebr. Since his mom passed last year we have been cleaning out her home & came across the siren that had been long forgotten about. Can anyone tell me anything more about it, why did the ordnance plant need this siren & what is it's value, does the ordnance plant label make it more rare, how many are still out there? We would love to know more!