This is a thin plastic (about 1mm thick) cover a little over the size of some Japanese made play mats used for card games and such and can fit 35cm x 52cm or 37cm x 57cm mats. The pictures show an example of how to install the mat on a typical Japanese play mat (mat is not included and for example only). There is a breathing hole punched in the bag so it is NOT waterproof. It may be used to protect the mat from casual use. It has a self adhesive flap to close the bag. Since the bag is wider than the mat, you may use tape to fold back the excess part as seen in the pictures. 

Please contact me for any questions. Shipping is free in the USA.