Good choice for dark/low light aiming - Meprolight AR15/M16 4 Dot Peep Rear Night Sights

The 4 tritium dots have a gentle glow that isn't noticeable in daylight or even typical indoor lighting. In deep shade to complete darkness, the glow of the rear dots blurs a bit, but is still visible, allowing fast alignment with a tritium or phosphorescent front sight post.

While not as easy of a sight picture as a red dot or other illuminated optic, don't need to be turned on, can't turn off, and can't accidentally be turned up bright enough to affect one's low light vision.

I installed this rear sight on a Midwest Industries fixed rear sight on a .458 Socom AR pistol for backcountry adventures in grizzly country. It was part of keeping that build under 4.5 lbs.