Most red dot sights use a battery to illuminate the diode used for the dot. My luck is none too good and I'm sure the battery would die at an in opportune moment.. Tritium is a glowing radio active gas and the sights using it are almost always more expensive.. Still I've used red dots on SKS rifles and pistols and they work well. For defense reliability is a very important concern,. My 870 has no sights just now.. perhaps a laser at some point..
