Definition: The topsheet is the outward layer of rubber in a sandwich rubber. It is made of ordinary pimpled rubber, which can be used with pimples facing in so that the smooth surface of the topsheet is used to hit the ball, or with the pimples facing out so that the smooth surface of the topsheet is glued to the sponge, and the pimples are used to hit the ball.
When no sponge is used, the topsheet is usually just called the rubber. In this case, the smooth side must be glued directly onto the blade, so that the pimple side is used to hit the ball.
