The karate tatami is the surface on which kumite and kata bouts take place. The WKF approved tatami is of "puzzle" type, formed by two pieces of 1m x 1m, 2cm thick, that are ed together with a system that stops them from separating while the tatami is being used during training or competition. Their colour is blue and/or red. The tatami must be made of a material with an impact absorption rate which complies with the WKF regulations, to protect the contestants if they fall. The pieces forming the tatami must have two different sides: they must be non-slip on the side in contact with the floor and the upper side must have a friction rate that is compliant with the WKF regulations in order not to provoke excessive friction that may cause injuries and, at the same time, to avoid the contestants from sliding.