Most metals retain cold much better than other materials like plastic and polyurethane because they’re good thermal conductors. We chose aluminum as it’s a cleaner metal that does not rust while being lightweight compared to other metals like stainless steel. Also some of the other ice rollers on the market have a thin aluminum or stainless band around a hollow plastic roller, while the roller in the Hot Mess Ice Roller is solid aluminum - because of this denser use of aluminum, it helps hold the cold for much longer.