Optional accessories for the Mossberg 500/590 can certainly be handy tactical upgrades. One essential upgrade you’ll need to make is in the sighting department. The tritium sight, for example, is perfect for helping you see where you’re aiming in the dark. The tritium sights are basically night sights that have a self-illuminating feature. The illumination is caused by the small trace of glowing tritium gas inside of the sight. This tritium gas can stay illuminated for years before you need to replace the sight. This will save you money from having to purchase batteries for red dot sights or constantly replace your sighting with a newer one. Anyone in the military or law enforcement will certainly find this nighttime sight particularly useful.