I'm not sure how this stupid thing is supposed to work, but it's clearly not reliable. The day two visit shows that the flat metal internals of my camera, like the aperture, are enough to set it off, as are things like cases for glasses. The enforcement is also very poor, as they found my slipjoint, but didn't press any further and thus missed the three other knives I was carrying

. I don't mind admitting that because, as the guard stated, the knives don't violate any laws, just that particular location's policy. Good thing I wasn't a nutcase.