An ingenious device to warn pedestrians and children that a car is about to reverse. There are many types on the market but this is the only one I know of that requires no DIY, no wiring and no electrical knowledge. If you can change an auto bulb, you can fit this gadget! Just remove your reverse light bulb and replace with this. Your reverse light still works as a light but is now also a warning beeper! Fits reverse lights that normally take a 21W level pin single contact bulb but is only suitable for negative earth vehicles (all modern vehicles and most classic vehicles from around 1975).