4TRONIX Educational Traffic Light for Raspberry Pi - 

The Pi-Stop is a low cost hardware module designed to allow Raspberry Pi users to take their first steps into interfacing with the real world. Designed with the learning in mind, everyone will recognise and identify its familiar elements encouraging their use along-side their own projects. The Pi-Stop is designed to remove many of the common hurdles people are faced with when getting started using hardware with the Raspberry Pi. Often it is difficult to know what components to use and how to connect them, the Pi-Stop makes it simple by plugging directly onto pre-set positions on the Raspberry GPIO connector. By plugging the Pi-Stop directly on to the Raspberry Pi GPIO header, no extra cables or wires are needed. Unlike many other add-on boards, they do not block unused GPIO pins, keeping them open for other uses. The Pi-Stop can be fitted in 4 standard locations, allowing up to four Pi-Stops to be controlled independently or combined with other hardware.