- Sapphire crystal with anti-reflective coating
- Constant night visibility for up to 25 years
- Uni-directional rotating bezel
- Lithium long life battery last 8+ years
- Protected, screw in crown and caseback
For over 20 years, Luminox has partnered with the world's toughest maritime commandos to continuously hone and refine a watch tough enough and useful enough to be considered first line gear for the finest warriors. In World War II, during the era of Frogmen and beach landings under fire, if a piece of diving gear wasn't on the ANU (Authorized for Navy Use) list, you didn't use it. The ANU list of equipment provided these Frogmen of the past and the Navy SEALs of today with a sense of security that their gear would work when needed. It is with this same intent that Luminox named these newly developed watches, the ANU series. If you have an essential mission then use authorized essential gear, ANU by Luminox. Water resistant to a depth of 200 meters, the 4220 can handle tons of pressure. Equipped with the Luminox self-powered illumination system, visibility is never an issue, even during long and deep night dives.