It is a bamboo or reed screen made by knitting thin bamboo sticks or reed sticks at equal distance to be hung over a window. People used to sleep while leaving windows open at the time when no any air conditioners were produced or used in Japan, so they used a sudare to block out window and let in the air in at the same time. The sudare is still used for protection from the sun today, even though the air conditioners are widely used. The items arrive in stores such as DIY home centers and hundred-yen shops when summer comes.