Tacky Rubber
These rubber sheets offer good control and, because of the rubber's sticky nature, enhanced Spin opportunities against slow balls.
Hardness of Sponge
Soft:
The ball stays on the rubber a fraction of a second longer because of the sponge's softness, giving more control and feel but a slight loss of speed. Soft rubbers are easy to use and often have a distinctive sound when you hit the ball.
Medium:
The standard sponge offers a happy medium between the Soft rubbers' ball control and Hard rubbers' increased speed.
Hard:
The ball rebounds almost immediately from the rubber because of the sponge's hardness, resulting in increased speed but less ball control. Most top professional players use hard-sponge rubbers for their increased speed, and the slight loss of control is less noticeable because they spend many hours practising to perfect it.
Thickness of Sponge
The rubber sponge is available in different thicknesses. Generally, the thicker the sponge, the more speed and spin it produces on topspin shots, but it reduces control. The reverse is true for backspin defensive shots: a thinner sponge increases backspin.