A refrigerator includes a displacer coupling structure, wherein one of two coupled displacers protrudes into the other of the two coupled displacers to the extent that an end of a regenerator built in the one of the two coupled displacers positions itself inside of the other of the two coupled displacers. The sound processor contains an inductive coil that may be tuned to an external charging coil for battery recharging. One phalange is adapted to be secured to a base. The closing elements bearing the roll may be discs or polygonal plates provided with annular groove for receiving the ends of the cylindrical body and with a pipe stub fitting inside the roll. The participant identification system analyses the received captured image including the identifying of an identification of the participant and then transmitting the captured image and the participant’s identification.