Transcription: A mouse lets you control an on-screen pointer to make menu selections and to manipulate graphics and text on your screen. This mouse has no feet. Instead, a small ball sticks through its underside housing. When you move the mouse, the ball moves too. As the ball turns, it rubs against two rollers and they also turn. One roller senses when the mouse moves side to side. The other roller senses up and down movements. the two rollers can tell which direction you move the mouse.
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