Automatic Time Setting-the Clock Has a Preset Time, So There Is No Need to Worry about Setting the Button. Simply Select Your Time Zone at the Bottom of the Clock and Turn on DST (If Applicable). Insert the Clock into the Approved Power Supply. Daylight Saving Time (DST) Quick Adjustment-to Quickly Adjust Daylight Saving Time, Slide the DST Switch at the Bottom of the Clock to on to Add an Hour (1 Hour). For Standard Time, Switch to off to Subtract One Hour (-1 Hour). High/Low Dimmer Control-Adjust the Display Brightness with High/Low Dimmer Control. Backup Battery-Button Battery Is Pre-Installed for Backup Battery and Time Setting. It Is Located in the Screw Fixing Cabinet at the Bottom of the Clock. This Battery Can Be Used for Several Years. Time Zone Selection-the Default Time Zone Is the Eastern Standard Time. before Inserting the Settings at the Bottom of the Clock, Your Time Zone.