Wentworth 11 inch x 15 inch 2 Piece Ultra Mat Set The mats can be used between -40 degrees to 480 degrees F. They are designed for all types of ovens and will help provide even heat transfer. They are made of fiberglass and silicome to highest European standards and conforms to US regulations on food grade silicone Have a standard life of 2000 to 3000 uses. Each mat measure 11 x 15 inch