A table tennis rubber is made from a combination of a top sheet and a sponge (except for Rubbers without sponge).

Top Sheet


The top sheet is the surface on which the ball hits. Therefore, the performance or characteristics of the top sheet has a significant influence on the game. Butterfly rubbers are available in black and red top sheet colors for each rubber. As stated in the ITTF Rules, "The surface of the covering material on a side of the blade, or of a side of the blade if it is left uncovered, shall be matt, black on one side, and of a bright colour clearly distinguishable from black and from the colour of the ball on the other". This means if black rubber is applied to the forehand side, red rubber must be applied to the backhand side (or vice versa). There is no difference in rubber performance between different top sheet colors.

Sponge


The sponge thickness/hardness varies the performance of the rubber which influences your game.

Sponge Thickness

Each rubber has a lineup of multiple sponge thicknesses. You can choose your sponge thickness depending on the performance you desire.
thin sponge thick sponge
Thin ← Sponge → Thick
Light ← Weight → Heavy
Low ← Bounce → High
Defensive Play ← Suited for → Offensive Play

Sponge Hardness

The hardness of the sponge is measured by Butterfly's own standard. The higher the value, the harder it is, and the lower the value the softer it is.
soft sponge hard sponge
Soft ← Sponge → Hard
Light ← Weight → Heavy
Low ← Bounce → High
Large Amount ← Ball absorbed → Small Amount
Slow Swing ← Suited for → Fast Swing
Beginners ← Suited for → Advanced Level

Lineup of Sponge Thickness

MAX: 3.8–4.0 mm (including top sheet)
2.1: 1.9–2.2 mm
1.9: 1.7–1.9 mm
1.7: 1.5–1.7 mm
1.5: 1.3–1.5 mm
1.3: 1.1–1.3 mm
1.1: 0.8–1.1 mm
0.5: 0.4–0.7 mm