So, I had too much time on my hands today and took a tube from a roll or paper towels, wrapped it in foil and stuck it on a cheap tripod and put it in my yard. I added a couple of electronic gadets, including a dead phone, and watched lots of brake lights as cars drove up my street. This does nothing other than slow down cars. And it works like a dream. I plan on putting it out occasionally so people get used to thinking they might get popped by a speed trap but not get used to not getting popped.