The 5mm colour changing LED slowly changes colour through Red/Green/Blue/red-green/green-blue and back to red. It is a flexible and economical way of creating mood lighting on a small scale and thus suitable for key stage 3 projects. Each LED is powered by a 5v open-ended USB cable that is supplied with this kit. The LED can be powered by any USB output including mobile phone chargers. More than one LED can be used per USB output but LED's will not light in sync. A wire connector is also supplied to make the connection between LED and USB easier so you can produce designs without the need of soldering. Alternatively the kit also comes with a 15mm switch and 100mm wire, a good way to introduce soldering.