Playing surface(s) of the Racket or Paddle must be covered by sponge & rubber sandwich sheet no thicker than 4 mm. One side of the racket must be RED and the other BLACK. At least 85% of the thickness of the racket must be made of natural wood. Plastic paddles and paddles with sandpaper, bare-wood or sponge-only coverings are not table-tennis rackets. For USATT-sanctioned tournaments, all rubber sheets must have an ITTF or USATT stamp of approved logo.