Poron Micro 5S

Having a voice to count down the distance is a good idea, although you have to put up with a New York accent. The sensors on the Poron were the smallest of those we tested, but their opaque white plastic housings meant they would need to be spray-painted to stop them standing out. The system worked well when reversing towards a car, but issued an alert from four metres, which was too early. It completely failed to spot the bicycle and had trouble seeing the bollard.