Why is the bat of table - tennis red and black?

A Table Tennis bat requires one of the sides to have a red rubber and the other to have a black rubber. A player is not required to have the same rubber on either side of the bat such that each side of the bat reacts differently. One side may be a high spin rubber while the other acts as an anti-spin. By making each side of the bat a different colour lets an opponent know how the rubber will react when hit off it.