Pimple out rubber
Table Tennis rubbers can have the pimples (pips) facing outwards or inwards.
Pimpled rubber (pips) has the pimples is attached to the sponge. So you strike the ball with the pimpled surface.
Pimples out are available in three basic varieties - short pimples, medium pimples & long pimples - and each one gives you a completely different effect when the ball is struck by the pimples.
Short pimples and medium pimples are suitable for players with a fast blocking or counter hitting game, whilst long pimples are suitable for a more defensive style of play. They can also help you to return attacking / offensive shots with unusual spin.
The majority of pimples out rubbers have different thickness of sponge underneath them, but there are some which do not have any sponge at all underneath them, and these are referred to as "OX"