This fly thing was probably the first thing I noticed that was unique about Amsterdam during our first trip there several years ago. Had to make a stop just after leaving the customs area at Schipol. Sure 'nuff, there was the fly on the urinal. Not sure if it improved my aim, but certainly provided some interesting conversation.

Works GREAT! Aim at the fly and you walk away with dry pants. Just shake or tap...

A colleague of mine claimed that they are heat sensitive and change colour in response but I have not noticed this myself. I reckon he had been waiting too long on the taxi in from the new runway.