Digging Futon. Horikotatsus size may vary slightly depending on the household, but this product has a cut-out opening so you can adjust the size of the hanging portion. Can be used with openings up to 37.4 inches (95 cm). There is also fabric at the entrance of the Horiho, so you can feel it just as warm as it prevents heat and burns from the back of the knee and the thigh. This is very valuable among many hollow-out types. Product: Origotatsu Futon, Rectangular, Product Size: 74.8 x 94.2 inches (190 x 240 cm), Opening: 35.4 x 47.2 inches (90 x 120 cm), Outer Material: 100% Polyester, 10 mm urethane foam.