Buyers must choose between Steel Panel, Aluminum, and Cast Iron. Steel panel radiators are the most common due to their cost-effectiveness and high heat output efficiency. Aluminum radiators offer superior thermal conductivity and faster response times, making them ideal for energy-saving projects, though they require pH-neutral water to prevent corrosion. Cast iron is preferred for heritage restoration due to its high thermal inertia, though it is significantly heavier and more expensive to ship.