Material: Resin Boil egg as per your choice No more hard or soft egg concern Diameter: 55 mm x 40 mm approx. Temperature resistant: 650 This egg timer will take the guess work out of boiling eggs! As the timer heats up, the red face changes color, indicating soft, medium, hard and stages in between, absorbing heat exactly as an egg does. The result is the perfect boiled egg! You just put the boiled egg timer and eggs into the pot and wait. Soft, medium and hard boiled line on egg timer will tell you the doneness degree of eggs.