Cake pans, for baking layer and other kinds of cakes, may be round, square, or rectangular, or even shaped like a heart or other form. Standard round pans are 8 and 9 inches (20 and 23 cm) in diameter with 1 1/2- to 2-inch (4- to 5-cm) sides; 10-by-3-inch (25-by-7.5-cm) pans are used for tortes and cheesecakes. Some have removable bottoms. Other common shapes and sizes: 15 1/2-by-10-by-1-inch (39-by-25-by-2.5-cm) baking sheet or jelly-roll pan; 8 or 9 inches (20 or 23 cm) square with 2-inch (5 cm) sides; 13-by-9-by-2-inch (33-by-23-by-5-cm) baking pan. Choose good-quality heavy metal pans. If using black steel or dark anodized aluminum, which absorbs heat faster, you may have to reduce oven temperature by 25°F (14°C).