The USB mouse used by a number of Macintosh computers contains a retainer ring that can be locked to deter its removal.

To lock the retaining ring, insert a straightened paper clip into the hole on the plastic ring and press down on the paper clip while you turn the ring clockwise (see Figure 1). The mouse ring is locked when the ring clicks into a position where it is at a slight angle to the rest of the mouse.

Figure 1 Locking the Retaining Ring.

To unlock the retaining ring insert a straightened paper clip into the plastic ring and turn the ring counterclockwise.

This information can also be found in the Mac OS Help online guide included with your computer.