Two lighting modes: 50% and 100% brightness. You can choose the right level for reading, and it remembers the last brightness setting you selected. USB rechargeable: built-in USB charging interface; connect directly to a laptop, power bank, car charger or USB socket for charging; no extra cables required. 200 mA lithium battery; charging time approximately 1.5 hours; runtime about 8 hours at the selected brightness. Rechargeable design eliminates disposable batteries. Compact and lightweight: weight 39 grams; mini format; clips to a book for nighttime reading; folds completely flat and slim; portable for reading on plane, train, or in the back seat of a car while traveling. Use scenarios: - Reading in bed without disturbing your roommate. - Traveling on plane or train by clipping to a book. - Reading in dim environments such as libraries or late-night study sessions.