Normally we know better than to buy any kind of spray anything being sold on the Internet, but PhotoBlocker is a special reflective spray that's supposed to be able to make it impossible for traffic cameras to capture an image of your car's license plate when you're speeding or running red lights. The FAQ says it all:
Q. Is this product legal?
A. YES. The law in most countries requires your license to be legible to the naked eye. PhotoBlocker Spray is a high gloss, clear, reflective spray that is undetectable. It causes no distortion nor does it obstruct your license plate's view. YOUR LICENSE PLATE WILL BE VISIBLE TO THE NAKED EYE. Besides, no one will even know you have it on. It only fools the cameras.