The green lights indicate the 3 minutes you should be in the pump and red lights indicate the time out of the pump. This can then be repeated 3 times for the manufacturers recommendation of how to use the pump. Most people don't wear a watch (or glasses!) in the shower so the lights and beeps make it visual and audible to give the time needed when using the pump. It comes with 2 sized suction cups, 1 to fit onto the pumps and a larger one if the user prefers it on a shower screen or tiles.