Abstract: An elongate flexible package (10) adapted to contain and either enhance or contribute to the control of the heating efficiency of an elongate heating element contained therein and having sufficient flexibility to conform to the item to be heated to which it is secured. Package 10 is provided with a first layer (1) made from a flexible heat conductive or heat insulative material and a second layer (2) made from a heat insulative material that is secured along the length of package 10 to the side of first layer (1) that faces away from the item to be heated to which package (10) is secured. A third protective layer (3) is disposed over second layer (2) and a cavity (4) enclosed by a portion to the walls of layers (1), (2) and (3) extends along the length of package (10) having a cross-sectional configuration adapted to contain and permit the heating element to be axially inserted into or removed from package (10) without having to remove package (10 ) from the item to which it is secured.