The TSP Sponge Meter is a must for all the tournament players and the tournament referees. The glass in the TSP Sponge Meter shows the thickness of the rubber magnified.

A great investment to save you from disqualified in the tournaments.

ITTF Rule about rubber thickness: "A side of the blade used for striking the ball shall be covered with either ordinary pimpled rubber, with pimples outwards having a total thickness
including adhesive of not more than 2mm, or sandwich rubber, with pimples inwards or outwards, having a total thickness including adhesive of not more than 4mm."