Plate steel fireplaces offer a more contemporary design than cast iron due the smooth lines and limited joints necessary in the manufacturing process. Plate steel fire places heat up and radiate heat quicker than cast iron but they do not retain the heat as long as cast iron. Plate steel comes in various thicknesses. 2mm steel is often used in decorative finishes and on some of the ‘convection’ panels that do not take the brunt of the heat from the fireplace. The structural parts of the fireplace, such as the firebox, are generally fabricated from 4mm steel which is lined with thermiculite brick (in the case of the firebox) to increase longevity of the firebox and the stove. All plate steel fireplaces in the Invincible range come with a 5 year limited guarantee and are manufactured to ‘CE’ standards.