Meprolight M21 Day and Night Reflex Sight
- Magnification Minimum: 1x
- Magnification Maximum: 1x
- Night vision: Yes
- Material Type: Aluminum
Last refreshed Jun 22, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
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ASIN: B0DCGLG3H5Model: M21Category: Rifle Scopes
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Overview
A battery-free reflex sight that runs on tritium and fiber optics, automatically blending ambient light with a tritium-lit reticle so it works day or night without switches or batteries to manage.
Despite sitting under a Rifle Scopes category label, this isn't a magnified scope, it's a red-dot-style reflex sight with a 30mm lens and an open reticle, built by Meprolight for military and law enforcement use. It ships with a quick-release adapter, so mounting and removing it from a rail is meant to be fast rather than a tool job. Reviewer experience across multiple platforms confirms it mounts to AR-pattern rifles, shotguns, and pistol-caliber carbines using that adapter.
- Tritium and fiber-optic powered, no batteries
- 30mm lens with open reticle
- Quick-release rail adapter included
- 10-year tritium warranty
Who it's for
Owners of AR-pattern rifles, shotguns, or carbines who want a rugged, always-on sight without battery maintenance. Suits those prioritizing durability and reliability over the finest reticle precision of a premium illuminated red dot.
Pros and cons
- No batteries or switches to manage
- Quick-release adapter mounts and detaches fast
- Co-witnesses in the bottom third with AR iron sights
- Some washout reported when transitioning between bright and dark lighting
Specifications
| Brand | Meprolight |
|---|---|
| Model | M21 |
| Construction & materials | |
| Material Type | Aluminum |
| Color | Black |
| Included components | |
| Unit Count | 1 |
| Other details | |
| Magnification Minimum | 1x |
| Magnification Maximum | 1x |
| Night vision | Yes |
| Sport Type | Shooting |
Frequently asked questions
Does the Meprolight M21 need batteries?
No. It runs on tritium and fiber optics, switching automatically between the two depending on ambient light.
What does it come with?
The sight, a quick-release adapter, a black dust cover, a lens cleaning cloth, a dust brush, and a user manual.
Does it work for low light and night use?
Yes, the tritium light source keeps the reticle visible at night, with a warrantied luminance life of 10 years.