The Nemo? 2000 is o-ring sealed with a twist-on shroud and comes with a polarity battery guard tray that safeguards against dangerous "outgassing" of hydrogen from an accidentally reversed cell. It is powered by 3 C alkaline cells, submersible to 500 feet, and has an ABS resin body which resists chemicals, corrosion, and extreme temperatures. Unlike ordinary flashlights that produce a yellow beam, the Nemo? 2000's incredibly bright Xenon lamp produces a powerful collimated white beam. Pelican's Nemo? 2000 is the leader in quality and performance.