Agents in a contact center are grouped dynamically by defining performance metrics against which agents are to be judged, and generating an evaluation score for each of a number of agents by comparing their actual performance data to the defined performance metrics. Two holding grips are connected to eyes located adjacent to one another. The pressurization of a space between the second and the third piston loads the second and third pistons in opposite directions. After video signal recording is ended, the digest video signal is recorded on the magnetic tape section. The air introduction portion further includes a gas-permeable film positioned on the movable member and closing the air passage. The arms form an angle that depends on a size of the capsular bag into which the size indicator is placed.