The Land based unit eliminates night and early AM congregating by disturbing the geese just enough to encourage them to move to another location. Solar power recharges the batteries making this free of maintenance, along with effective coverage up to 75 yards from placement makes this ideal for keeping the geese away. Unit uses a Nickle Metal Hydride (NiMH) battery. The whole light is replaced when the old light stops working. Comes with a 2 year warranty.