[. . . ] [. . . ] GREENLEDs:(Zone 1): The green LEDs flash when in Zone 1 of an alert area. MEM/DEL: This button is used for storing or deleting user coordinates. MUTE/DIM: If, when approaching an alert area, you wish to stop the audible alert but still receive a visual alert, press this button. If you want to reduce the brightness of the LEDs press this button when you are not receiving an alert on the unit. [. . . ] [. . . ]