The display will only be backlit continuously when connected to a power source with the included USB cable or a DC adaptor (not included). 3 x AAA batteries (not included) are required to retain time and alarm settings. Features & Specifications:– 12 or 24-hour format– LCD screen– Alarm and snooze function– Temperature display 0-37C– Night screen brightness setting– Weather forecast prediction moon phase– USB power cable included – Material: Acrylic, LCD – Colour: White/Black – Movement: Digital – Power:Connect to DC or 3 x AAA Batteries (Not Included) – Dimensions: HWD 14 x 10 x 8 cm / 5.5 x 3.9 x 3.1in – Weight: 0.25kg