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: – Size: HWD 13 x 19 x 5.9cm; 0.32kg – Materials: Acrylic case, LCD screen – Colour: Matt Black case, white/black/yellow/red screen – Movement: Digital – Power: 1x USB cable included, 3 x high-quality branded AAA batteries (not included)