Leupold’s® industry-leading knowledge of waterproofing and “ruggedizing” has been the cornerstone of our riflescopes for well over half a century, and we have brought the same level of robust design and waterproofing to our new MX™ Modular Flashlight system. Leupold MX Modular Flashlight multi-mode models utilize a sophisticated magnetic sensor switch to seal the internal components of the Bezel from the elements. Double O-ring protection between the Tail Switch and Maintube, and Bezel and Maintube, provide waterproof integrity to 4 atmospheres [132 feet (40 meters)], even with the Tail Switch in the 1/8th turn lockout position. The functional submersion limit of 2 atmospheres [66 feet (20 meters)] is based on the level at which water pressure activates the switch in the unlocked position only.