The Color Changing Egg Timer sits in the pan with the eggs. It changes color as the eggs cook, so it's easy to see when your eggsÂ are ready. Graduated scales show when eggs are soft, medium or hard by sensing heat instead of time. The sensor accounts for the number of eggs, the amount of water, even the altitude at which the eggs are being cooked. Soft boiled eggs are exactly as you like them...every time. Hard boiled eggs are no longer over cooked, so they have perfectly colored yolks, and a smooth texture.