Electric VF photojammer

[cr500]

I have seen the VF photojammer advertised as being set off when a camera tries to take its photo. How does it work during the day when the camera doesnt use a flash? Or does it only work at night? If it does go off during the day ,will the light it shines on the plate have any effect?
Has anyone here tried them?

[worldpower]

Actually the light suppose to be so brilliant that it would work in tha day also,what im wandering is how long does this bulb last.