Primary Arms SLx MD-21 Red Dot Sight

Primary Arms SLx MD-21 Red Dot Sight Product Description

21 mm Microdot Design: The SLx MD-21 features a compact 21 mm tube, offering a balanced field of view and fast target acquisition for close- to medium-range shooting.

Multiple Reticle Options: Available with a 2 MOA red dot or ACSS CQB reticle, allowing users to choose between a simple aiming point or an advanced ballistic reticle system.

AutoLive Technology: Motion-sensing AutoLive automatically turns the optic on when movement is detected and powers it down when idle, extending battery life and ensuring readiness. 

Daytime-Usable Illumination: The illuminated reticle is visible in bright daylight and includes night vision-compatible settings for versatile use. 

Durable Aluminium Construction: Built from aluminium with fully multi-coated lenses, providing resistance to environmental conditions and consistent optical clarity. 

Precise Adjustment System: Features 14 mm/100 m (1/2 MOA) click adjustments with a total adjustment range of 100 MOA (≈29.09 MRAD) for both elevation and windage. 

ABOUT THE SERIES

The Primary Arms SLx series represents the brand’s core optics line, designed to deliver reliable performance, practical features, and strong value.

SLx optics are widely used across recreational, competition, and professional applications, offering a balance between affordability and functionality.

The series includes red dots, prism optics, and riflescopes designed for everyday use.

ABOUT THE MODEL Primary Arms SLx MD-21

This model is designed as a compact tube-style red dot sight for rifle platforms, offering durability and fast target acquisition in a lightweight format.

It features a 21 mm tube, illuminated reticle, AutoLive technology, and compatibility with Aimpoint Micro mounting standards.

Key specifications include 71.12 mm length, 141 g weight, CR2032 battery, 14 mm/100 m click adjustments, and total adjustment range of 100 MOA (≈29.09 MRAD). 

The optic is intended for shooters who require a durable and reliable red dot sight for close- to medium-range shooting applications.

ABOUT THE MANUFACTURER

Primary Arms is a US-based optics manufacturer known for delivering high-value optics and innovative reticle systems across riflescopes, prism optics, and reflex sights.

MAIN FEATURES

• Optic Type: Tube red dot sight
• Objective Lens Diameter: 21 mm
• Reticle: 2 MOA Dot / ACSS CQB
• Reticle Illumination: Yes
• Daytime-Usable Illumination: Yes
• Parallax: Free of parallax
• Adjustment: 14 mm/100 m / 1/2 MOA
• Adjustment Range: 100 MOA / ~29.09 MRAD elevation & windage
• Battery: CR2032
• Length: 71.12 mm
• Weight: 141 g
• Material: Aluminium
• Lens Coating: Fully multicoated
• Footprint: Aimpoint Micro standard
• Mounting Standard: Aimpoint Micro
• Color: Black
• Durability: waterproof, fogproof, shockproof

WARRANTY

10-year warranty covering material and manufacturing defects under normal use.

IN THE BOX

• Red dot sight
• Low mount
• bsolute Cowitness mount with spacer (1.41" or 1.535" Height)
• User manual