The LT150 is the perfect size. It is big enough and bright enough to use as your primary night diving light, yet it is not too big to get heavy in your hand. Using 3 C cells, this light boasts an output of 1000 lumens! With a magnetic slide switch that provides variable power, you control the battery duration. Slide it up for 1000 lumens for a 1-hour duration or slide it back to 40 lumens and get an amazing 30-hour duration. Magnetic slide switch offers variable output. Brightness: 40 lumens to 1000 lumens. Battery duration: 30 hours to 1 hour. Depth rated to 330’ (100 m). Uses 3 C cell batteries (not included). Overall Length: 9.1” (231 mm).