Spin Elastic Rubber
Rubber sheets that have the speed of the offensive elastic rubbers but with additional spin characteristics. Spin Elastic rubbers are the choice of rubber sheet for today's top table tennis professional players.
Hardness of Sponge
The ball stays on the rubber a fraction of second longer due to the softness of the rubber sponge which results in more ball control and feeling but results in a slight loss of speed. Soft rubbers are easy to use and often have a distinctive sound when you hit the ball.
The standard sponge offering a happy medium between the Soft rubbers ball control and Hard rubbers increased speed.
The ball rebounds almost immediately from the rubber due to the hardness of the sponge which results in increased speed but less ball control. The majority of top professional players use rubbers with hard sponge due to the increased speed possibilities and the slight loss in ball control is not as pronounced due to the many hours of practice perfecting their ball control.
Thickness of Sponge
The Sponge of the rubber is available in different thicknesses. Generally the thicker the sponge results in an increase in Speed and Spin when playing topspin shots but a decrease in Control. The reverse is true when playing backspin defensive play and a decrease in sponge thickness results in an increase in backspin.