The 5 Star Steel Door has two sheets of steel (27 gauge) wrapped around an insulating core, creating an extremely durable and energy-efficient door. Our 5 star models are perfect for any attached residential garage. These models are extraordinarily quiet, and are heavily insulated with polystyrene insulation. The insulation comes in standard polystyrene, or Intellicore Insulation which is warm, stronger, and quieter. This garage door is offered in two thicknesses, 1 3/8 inches, and 2 inches, more thickness equals better insulation.