Many of the higher quality lensatic compasses come with luminous markings on the dial as well as the sight so they are easier to use in the dark. Now, keep in mind that easier is a relative term. Night land-navigation is still very difficult with a compass and map, especially if you are beholden to the rules of noise and light discipline.

For those unfamiliar with those terms, it means you can't give up your position and really have no choice but to use a glow stick with a slit cut in the side of it for reading your map. When the luminous markings on your compass become dull, you can recharge them only after completely insulating your flashlight against any void where light might escape.

All that aside, there have been many questions over the years about the safety of this luminous material. To those in the know, the material is a mixture of tritium and a combination of phosphors, and is, in fact, radioactive. It is a radioactive isotope of hydrogen, and the low-grad radiation from the tritium actually causes the phosphors to illuminate. This only happens for about 12 years or so, when the life of the tritium is so far reduced that it is no longer effective at making the phosphors glow.

Other uses for tritium include nuclear weapons! That's right. Specifically, it is used in the primary detonation reaction of the weapon as a sort of jump-start for the whole process. Interestingly, small amounts of tritium are also used on the night sights of some weapons so that the operator can see the sight and line it up with his target.

There have been news stories over the years where workers in factories where compasses are assembled have taken tritium off the premises as a type of party trick. It has shown up at houses, in bars, at sporting events, all for the purpose of entertainment of the masses. These releases are generally not a big deal, other than that it's a controlled substance and should never be removed from the building where it is licensed for use.

The bottom line on tritium-infused compasses is that they're great to use in low light if you can't, or aren't allowed to use a flashlight or some other superior light source. However, if you don't feel you'll be in a situation such as that, it's a luxury that really won't benefit you and will cost a few extra dollars to have, dollars that could easily be spent elsewhere.