It's marketing blurb isn't it. I think that they are talking just about the housing. Some plastics become brittle when cooled repeatedly to freezing and then warm up again as we have every winter. This will not happen with steel. However steel is a conductor of heat and cold whereas plastic is an insulator, so unless the steel is insulated on the inside to compensate then it may more quickly conduct the cold inside and freeze the insides up. Looks nice and shiny though