Simmer ring

A simmer ring (also known as a heat diffuser) is placed between your stove burner and cookware. It spreads out direct heat to create a steady, low temperature. This prevents burning, scorching, and boiling over, and protects delicate cookware like glass or clay from cracking. 

A simmer ring is highly recommended if you regularly prepare delicate dishes like sauces, custards, and melted chocolate. It is also incredibly useful for slow-cooking stews or making rice, as it eliminates hot spots and ensures your food cooks gently without sticking to the bottom of the pan.