Heat 4-Burner Insulated Jacket HTX-INSJACK-4B. HTX-INSJACK-4B. This premium Insulated Jacket is specially designed for HEAT's excellent line of 4-burner gas grills. It's a safety essential in the process of installing a gas grill into an outdoor kitchen or island space. This insulated jacket is constructed of pristine stainless steel with a self-supporting ledge around the sides and back that adds one more layer of quality to your outdoor kitchen.