The Primary Arms SLx MD-21 ACSS-CQB brings the speed-focused ACSS-CQB reticle — a fine centre aiming point inside a large outer ring — to the value 21mm AutoLive red dot sight.
AutoLive wakes the sight on movement, side push-buttons cycle night-vision-compatible brightness, and the aluminium housing is waterproof and shockproof. Low and absolute co-witness mounts included.
How It Compares
Plain dot instead? The MD-21 2 MOA. Solar backup? The GLx MD-21S ACSS. New to ACSS? Read our ACSS guide; browse rifle dot sights.
Key Features
- ACSS-CQB reticle — centre dot + fast outer ring
- AutoLive motion sensing (CR2032)
- Side push-button brightness, NV compatible
- Low + absolute co-witness mounts included
- Waterproof, shockproof aluminium; lifetime warranty
Technical Specifications
| Reticle |
ACSS-CQB (red) |
| Power |
CR2032; AutoLive motion sensing |
| Size |
21mm micro |
| Mounts |
Low + absolute co-witness (included) |
| SKU / MPN / UPC |
PA-SLX-MD-21-ACSS / 810028 / 818500018261 |
What's Included
- SLx MD-21 ACSS sight, low mount, co-witness riser + spacer, CR2032, tools, manual
UK Delivery & Support
UK-stocked and dispatched tracked from our UK warehouse — no import duties or customs delays — backed by UK-based support and Primary Arms' lifetime warranty.
Frequently Asked Questions
Does the ring help with astigmatism?
Many astigmatic shooters find a ring shape easier to centre than a bare dot — see our astigmatism guide.
Is it night-vision compatible?
Yes — dedicated NV brightness settings.
