Why it is used igusa ( TATAMI ) for this mat? There are 3 effects !! Humidity control effect As it absorbs humidity and sweat, it is comfortable and dry Deodorant effect Deodorizes unpleasant odors such as sweat and ammonia odor Air cleaning Adsorbs harmful substances such as formaldehyde and creates clean air Product Description The back is made of PVC The grip with the floor has also improved. Material / FRONT -IGUSA (RUSH) BACK-PVC MADE IN JAPAN　 * DO NOT WASH -Clean with a dry cloth know more... ABOUT IGUSA AND TATAMI TATAMI was first made in the 1500s by weaving igusa (rush). Unique to Japan. Tatami mats were created with Japanese wisdom. They have been used for centuries throughout the country. FACTS ABOUT IGUSA The moisture absorbing of igusa is 2.5 times that of cotton. The honey-cornb like structure inside igusa enables it to absorb odors and harmful substances in air. The scent of igusa contains phytoncide which contrbutes to its relaxing effect flame retardant