The characteristics of the table tennis racket affect the quality of speed and spin imparted to the ball as well as control of trajectory. Rackets are often assembled by players from a blade made of all wooden layer(s) or mostly wood with a layer or two of other material, and two sheets of "pimpled rubber" which usually consist of a rubber topsheet with pimples on one side  glued onto a layer of cellular rubber "sponge". The composition, size and characteristics of rubbers and blades are regulated by the International Table Tennis Federation (ITTF) and published on their website in a handbook of rules and regulations.