Optimus 120-2113 - Manual (Page 10)

rubber grommet onto the mounting bolt.
Otherwise, you can use the supplied bolt and washer to attach one end
of the supplied metal strap to the mounting bolt on the back of the
stereo. If necessary, bend the metal strap to fit your vehicle's
mounting area. Then use the supplied sheet metal screw to attach the
other end of the strap to a solid metal part of the vehicle under the
dashboard. This strap also helps ensure proper electrical grounding
of the stereo.
10. Snap the plastic collar onto the front of the stereo.
11. Reconnect the cable to the vehicle battery's negative (-) terminal.
Note: You might need to reset the stereo's clock after you reconnect
the cable to the vehicle battery.
Removing The Stereo From The Dash
If you ever want to remove the stereo from the dash, follow these steps.
1. Disconnect the cable from the vehicle battery's negative (-) terminal.
2. If you secured the stereo to an existing mounting hole under the dash,
slide out the stereo to free the mounting bolt from the mounting hole.
Or, remove the bolt holding the metal strap to the back of the stereo.
3. Press REL to remove the stereo's control panel.
4. Snap the plastic collar off of the front of the stereo.
5. Insert both of the supplied keys into the slots at the bottom left and
right sides of the stereo. Press the keys downward and slide the
stereo out of the dash.
6. Remove the keys from the slots.
7. Disconnect the wire harness and the antenna.
8. Reconnect the cable to the vehicle battery's negative (-) terminal.