Both these bike lights are rechargeable so you\'ll no longer be caught short when there\'s no batteries in the house. From flashing to steady your needs will be suited perfectly and up to 5hrs burn time on the front and 30hrs on the back, these bike lights are sure to meet your needs when commuting. FeaturesRechargeable Front and rear bike light set80 lumen front light and 15 lumen on the back lightUSB chargingBattery indicator Battery Auto Save on the rear light - Converts to flashing mode when on low power so it last longerFlashing mode - 5hrs Front, 30hrs Rear burn timeConstant mode - 5hrs Front, 1hr Rear burn timeRapid - Rear light 5hrs burn timePulse mode - Rear light 20hrs burn timeCharge time - 1.5hrs for both