HexClad is tri-ply, which means it has 3 layers (you possibly hear about this lots with, say, All-Clad). First, there’s a layer of magnetic stainless steel (so it works on gas, electric powered, and induction cooktops). Then, a center layer of aluminum, which acts as the heating element, and one greater layer of steel. https://fortyreviews.com/home-kitchen/hexclad-reviews/