This 7-piece set cost around 210,000 yen. 7-layer construction. Diameter: 26cm High heat retention, shortens cooking time. Use high heat initially, then reduce to medium heat after adding water to the lid. You can even make soft-boiled eggs and sponge cakes with just a little water. Also, adding water to the lid creates an oven-like environment, making it a versatile piece of cookware. I have washed it, but there are a few minor stains on the lid. They are not very noticeable. Compatible with both IH and gas stoves.