*CONTACT US FOR A SPECIAL COUPON CODE!*
Primary Arms Optics® SLx® MD-21 Push-Button 21mm Microdot Sight – 2 MOA Red Dot Reticle – AutoLive® Motion Technology – Aimpoint® Micro Footprint Mount – Hardcoat Anodized Black – 810027
Product Description
The Primary Arms Optics® SLx® MD-21 Push-Button 21mm Microdot Sight (810027) represents a premier, battle-tested mechanical benchmark in close-quarters battle (CQB) target indexing, cross-platform weapon scaling, and low-profile electronic aiming logistics. Engineered in Houston, Texas, to fulfill the uncompromising duty needs of tactical operators, modern defense groups, and high-tempo competition marksmen, this ultra-compact enclosed mini reflex sight sets the standard for value-driven durability. While legacy micro dots utilize easily broken mechanical rotary knobs that snag on uniform webs or fail internally under intense lateral impact shear stress—and cheaper optics suffer from fuzzy emitter bloom—the MD-21 commands absolute tactical security. This high-efficiency microdot (818500018254) provides an indispensable primary aiming solution for AR-15 platforms, tactical shotguns, personal defense weapons (PDWs), and defensive pistol caliber carbines (PCCs).
The core performance victory of this advanced SLx engineering matrix relies on the integration of Primary Arms’ signature AutoLive® motion-sensing technology paired with top-mounted push-button controls. To eliminate the persistent threat of a dead battery during a critical home protection block or active field navigation string, the intelligent internal processor monitors physical movement and automatically places the emitter into a hibernation sleep mode after two minutes of total stillness. The exact split-second the optic notes a micro-vibration—whether from unholstering your sidearm, picking up your carbine, or stepping onto the range deck—it flashes the reticle back to life instantly at your exact previous brightness index. Powered by a common, highly accessible CR2032 lithium coin cell battery, this power optimization track stretches working operational longevity to an incredible 40,000+ hours on medium settings, ensuring your red dot is always active when lives are on the line.
The structural chassis of this 4.6-ounce powerhouse is precision-milled from a single monolithic billet of 6061-T6 structural aircraft-grade aluminum alloy and completed with a non-reflective, scratch-masking hardcoat anodized black armor wrap. Outfitted with premium fully multi-coated lens elements and an enclosed nitrogen-purged tube framework, the MD-21 boasts a severe-duty IP67 waterproof and fog-resistant rating capable of pushing through torrential rain walls, desert dust squalls, and deep freezing temperatures without internal condensation or optical drift. It features a crisp, ultra-precise 2 MOA Red Dot reticle that provides an immaculate balance between fast target acquisition up close and fine precision at intermediate ranges across 12 distinct illumination settings (including dedicated night-vision compatible modes). Utilizing the globally standardized Aimpoint® Micro T1/T2 mounting footprint matrix, this micro powerhouse includes both a low mount and an absolute co-witness mount with a modular spacer, giving you total mechanical and alignment authority over your defensive firearm layout.
Includes: (1) Authentic Primary Arms SLx MD-21 Push-Button Microdot Core (Hardcoat Anodized Black, 2 MOA Red Dot Reticle), (1) Lightweight Low Picatinny Mount, (1) Absolute Co-Witness Picatinny Mount with Riser Spacer, (1) Dual-Piece Bikini Rubber Lens Cover set, (1) CR2032 3V Battery, Torx Mount Hardware Screws, Adjustment Hex Wrench, Microfiber Polishing Cloth, Technical Manual, and Original Factory Branded Sealed Retail Presentation Boxing.
*Mounting Alignment & Torque Calibration Guidance: The Primary Arms SLx MD-21 is engineered natively to mirror the industry-standard Aimpoint Micro (T1/T2) mount interface footprint, supporting seamless integration with a massive library of aftermarket high-rise, quick-detach, or standalone optic mounts. When securing the red dot housing onto the included Picatinny base plates or an aftermarket rail, verify that all interface tracks are thoroughly clean and degreased. Apply a single drop of medium thread locker to the mounting hardware and torque the base screws to a strict specification of 12 to 15 inch-lbs maximum using an accurate inch-pound tool; over-compressing the fasteners will strip out the aluminum chassis threads. Windage and elevation changes are driven via low-profile, capped slot adjusters calibrated at 1/2 MOA per audible click detent. Prior to commencing workbench alignment loops, explicitly verify your host firearm is completely unloaded, cleared, and safe.
Key Features
- Smart AutoLive® Motion Sensing: Advanced motion-activated energy preservation loop sleeps the red dot during storage and wakes it instantly upon movement to maximize readiness.
- Crisp, Precision 2 MOA Reticle: The ultra-sharp 2 MOA center dot provides an uncluttered point of aim that minimizes target coverage, maximizing downrange precision out past 100 yards.
- Aimpoint® Micro Spec Footprint: Natively accepts standard Aimpoint T1/T2 configuration mounts, unlocking a limitless selection of specialty mounts, 45-degree offsets, and standalone QD bases.
- Dual Mount Combo Infrastructure: Ships complete with a low-profile mount and an absolute co-witness mount plus riser spacer, supporting customized setup heights on any Picatinny track.
- Enclosed IP67 Waterproof Core: Heavy-duty nitrogen-purged 6061-T6 aluminum housing isolates sensitive internal electronics from mud, dust, and water immersion.
- Tactile Top Push-Button Array: Replaces clumsy side-snagging dials with intuitive, low-profile top buttons for smooth brightness manipulation even while wearing thick tactical gloves.
Product Specifications
- Brand: Primary Arms Optics® (Designed, Field Tested, and Quality Evaluated in Houston, Texas)
- Optic Lens Series: SLx® (Proven Performance, Innovation, and Duty-Ready Tactical Value)
- Model Series Designation: SLx MD-21 Push Button 21mm Microdot with AutoLive®
- SKU / MPN: 810027 (Alternative Industry Identifiers: PA-SLX-MD-21 / MD-21 / SLXMD21)
- Optic Structural Class: Enclosed Tube Miniature Electronic Reflex Sight
- Optical Magnification Power: Fixed 1x Parallax-Free True Visual Alignment
- Clear Objective Window Diameter: 21mm Performance Optical Pathway
- Reticle Profile Geometry: 2 MOA Sharp Circular Center Aiming Dot
- Reticle Illumination Color: Brightness Red Dot Emitter
- Illumination Brightness Scale: 12 Total Manual Settings (Includes Night Vision Compatible Modes)
- Turret Adjustment Increments: 1/2 MOA Click Detents (Audible Mechanical Adjusters)
- Total Windage / Elevation Adjustment: ±40 MOA Comprehensive Internal Tracking Track
- Chassis Housing Material: Precision CNC-Machined 6061-T6 Structural Aircraft Grade Billet Aluminum
- Surface Protection Finishing: Highly Resilient Type III Hardcoat Anodized Matte Black Shield
- Optical Lens Multi-Coating: Fully Multi-Coated Scratch-Resistant & Anti-Reflective Optical Glass
- Power Battery Interface Requirements: Driven via Single (1x) CR2032 3V Lithium Coin Cell
- Onboard Battery Life Capacity: 40,000+ Hours Base Runtime (Stretched via AutoLive Sensor Loops)
- Ingress Protection Structural Rating: IP67 Waterproof Certified / Fully Fog-Resistant Enclosure
- Mounting Footprint Profile: Aimpoint® Micro T1/T2 & Standard Microdot Footprint Spec
- Included Base Mount Metrics: Low Mount + Absolute Co-Witness Mount with Spacer (1.41" to 1.535" Heights)
- Product Longitudinal Length: 2.50 Inches (Compact Space-Saving Handguard Profile)
- Product Net Bare Weight: ~4.60 oz (~130.4 g) Optic Base / ~5.00 oz with Mount Base Seated
- Total Packaging Shipping Mass: ~0.75 lbs (Enclosed Inside Heavy Padded Retail Presentation Box)
- Factory Warranty Matrix: Backed by the Primary Arms Optics Comprehensive Lifetime Warranty
- UPC Barcode Number: 818500018254
