A twice-up page, also known as double-up page, is a comic page drawn on a board twice the size of the printed material, with an image size of 12 x 18 inches (30.5 x 45.7 cm). Usual comic pages have an image size of 10 x 15 inches (25.4 x 38.1 cm). A few resources: Large Art vs Small Art (Prop Store)