Spode Baking Days Green Cafe Mug, Set of 4 4-14-Ounce Mugs Made of opaque white vitreous Stoneware Available in White,Black, Blue, Red, Green or Navy with White Polka Dots Oven Safe to 340 degrees; Dishwasher safe; Microwave safe Never place empty items in microwave or oven; Guaranteed against manufacturer defects; For further information please contact The Portmeirion Group at 888 778-1471