This pack of four RaySoar flashlights uses a 3535 red LED that emits at 620 to 625 nm. Red light is less likely to disturb animals, so the lights suit wildlife observation and hunting, and it also preserves night vision for astronomers reading charts or pilots reading checklists. Each flashlight has three modes (high, low and strobe) and a beam that reaches about 150 yards. Each takes one AA battery, which is not included.