Table tennis rubber is a type of rubber used as covering on a racket in table tennis. Modern table tennis rubber is usually composed of two layers: a layer of foam ("sponge") underneath and a layer of actual rubber on the surface. There are four common types of table tennis rubbers: short pips, long pips, antispin, and inverted. The thickness and density of the sponge layer underneath also affects how the rubber will handle the ball. Because of the large variety of table tennis rubbers, there are a larger variety of playing styles in table tennis than in other racket sports. History Rubber was first used in table tennis with the rise of hard racket paddles in the 1930s; the rubber consisted of short pimples over a wooden blade. In the 1950s, the sponge racket was introduced. It had a layer of foam underneath the layer of rubber. The foam helps provide more spin and speed. The International Table Tennis Federation (ITTF) regulated the thickness of the foam + rubber layer to a maximum of 4 mm ( inch) thick, which has been the regulation in table tennis since. Until 1986, players often had the same color of rubber on both sides of their paddle so that opponents could not tell which side of the paddle was being used. On July 1, 1986, two years before table tennis's introduction to the Olympics, the ITTF made it a rule that competition paddles had to have black rubber on one side and red rubber on the other side. Types of rubber Table tennis rubber has four common types: inverted and short pips rubber are primarily offensive, while long pips and antispin are primarily defensive. The word "pip" refers to the usually conic-shaped raised bumps on top of the rubber in short and long pips rubber or the bumps on the inside attached to the foam on inverted or antispin rubber. Inverted Inverted rubber is an offensive rubber and the most popular type of rubber. They are smooth on the outside, leaving the pips on the inside touching the foam, which is why it is called inverted. Inverted rubber's wide variety of speeds and spins make it a favorite among players. Manufacturers will provide speed and spin ratings to differentiate their type of inverted rubber from others. The faster the speed rating, the harder it is to control. Tensioned rubber Before 2007, professional