In the modern shooting landscape, the speed of technology often outpaces the simplicity of integration. With dozens of manufacturers producing red dot sights (RDS), each utilizing different footprints, heights, and mounting standards, the most common question we encounter is: “What Sidelok mount do I need for my optic?”
The KDG Sidelok™ system represents a paradigm shift in optic mounting. It is a patented, tool-less, quick-detach (QD) system that offers a true return-to-zero guarantee. However, the system is only effective if you pair the right mount with the right footprint.
This guide is the ultimate resource for matching your red dot or prism optic with the correct Sidelok model, ensuring your setup is secure, modular, and perfectly aligned.
What is Sidelok™ Technology?
Before diving into compatibility, it is essential to understand why the Sidelok system is the professional choice for mission-critical optics.
Traditional QD mounts rely on levers or knobs that require manual adjustment and can snag on gear. Sidelok utilizes a camming attachment system driven by a single push-button.
- Tool-Less Operation: You can mount or swap optics in seconds with zero tools.
- Security: The system features a secondary locking mechanism to prevent accidental detachment.
- Repeatable Zero: Precision machining ensures that when you remove and re-attach your optic, your point of impact remains unchanged.
The Compatibility Matrix: Finding Your Footprint
To choose the right Sidelok, you must identify the footprint of your optic. We have categorized every major optic on the market into their respective Sidelok models below.
1. The 30mm Tube Standard (SID5-110)
This mount is designed for traditional “tube-style” red dots that utilize a 30mm diameter housing. These are the workhorses of the tactical world.
- Compatible Optics: Aimpoint PRO, Aimpoint Comp M4, SIG Sauer Romeo7.
2. The “Micro” Footprint (SID5-120 & SID5-121)
The “Micro” standard (pioneered by the Aimpoint T-1/T-2) is the most popular mounting interface in the world. KDG offers this in two heights: SID5-120 (Lower 1/3 Co-witness) for a less cluttered sight picture, and SID5-121 (Absolute Co-witness) for those who prefer their irons centered in the glass.
- Aimpoint: Micro T-1, T-2, H-1, H-2, Comp M5, Duty RDS.
- Holosun: 403 Series, 503 Series, 515 Series, 530 Series.
- SIG Sauer: Romeo4 (post-2016 models), Romeo5.
- Vortex: Crossfire.
- Primary Arms: SLx Advanced Micro Dot, MD-20, MD-21 Series.
- Others: Athlon Midas TSR2, Blaser RD17, DI Optical SP1, Bushnell Optics.
3. The ACRO & MPS Revolution (SID5-125)
Closed-emitter “mailbox” style optics are the new standard for durability. The SID5-125 is engineered to handle the specific interface of these ruggedized sights.
- Compatible Optics: Aimpoint ACRO (P1/P2), Steiner MPS, Lead & Steel Pandora PB-3, Burris FastFire E, Gideon Mediator II.
4. The DeltaPoint Pro & EFLX Standard (SID5-250)
Originally designed for handguns, these large-window optics are increasingly popular as primary rifle sights or on offset mounts.
- Leupold: DeltaPoint Pro.
- SIG Sauer: Romeo X-Pro, Romeo X-Pro Enclosed.
- EOTECH: EFLX, EFLX CE.
- Holosun: SCS-320.
- Vortex: Defender ST, Defender XL.
- Bushnell: RXS-100, RXS-250.
5. The Trijicon MRO Specialty (SID5-220)
The Trijicon MRO features a unique footprint and a larger objective lens than standard micro-dots. The SID5-220 is custom-profiled to match the MRO’s body perfectly.
- Compatible Optics: Trijicon MRO, Burris RT-1X.
6. The RMR & SRO Dominance (SID5-230 & SID5-231)
The RMR footprint is the industry standard for “open emitter” sights. We offer the SID5-230 (Absolute Co-witness) and the SID5-231 (Low Profile) for different application needs.
- Trijicon: RMR (Type 1 & 2), RMR HD, RCR, SRO.
- Holosun: 407C, 507C, 508T, 507Comp.
- Swampfox: Liberty, Justice, Kingslayer.
- Primary Arms: SLx RS-10.
- Others: Gideon Storm, Gideon Omega, Gideon Alpha, Riton 3 Tactix PRD.
7. ACOG & Prism Optics (SID5-240)
Prism scopes offer etched reticles and magnification but require a rock-solid base. The SID5-240 replaces the factory thumb-screw mounts for a faster, more secure interface.
- Trijicon: ACOG, VCOG.
- Primary Arms: SLx 3x Prism, SLx 5x Prism.
- Vortex: Spitfire HD Gen II 3x, Spitfire HD Gen II 5x.
- SIG Sauer: Bravo3, Bravo5.
Absolute vs. Lower 1/3: Which Height is Right?
When choosing between models like the SID5-120 and SID5-121, you are choosing your optical centerline height.
- Absolute Co-Witness (SID5-121 / SID5-230): This puts your red dot at the exact same height as your iron sights. When you look through the glass, your dot will sit right on top of your front sight post. This is preferred by shooters who want a consistent cheek weld across all sighting systems.
- Lower 1/3 Co-Witness (SID5-120): This raises the optic slightly. Your iron sights will sit in the bottom third of the window, leaving the center of the glass clear and unobstructed. This is the preferred choice for tactical shooters who want maximum visibility and a more “heads-up” shooting posture.
Why Sidelok Over Traditional QD Levers?
The market is flooded with “Quick Detach” mounts, but most fail the professional-use test.
- No Manual Tensioning: Traditional QD levers require you to tighten a nut to get the right “feel.” If it’s too loose, you lose zero; too tight, and you break the lever. Sidelok is self-adjusting to the rail.
- Snag-Free: There are no protruding levers to catch on your plate carrier, barrier, or brush.
- True Return to Zero: Because the camming action is consistent every time the button is pressed, the mechanical tension remains identical. This is why Sidelok is trusted for optics that require a precise zero, like the Trijicon ACOG or Aimpoint Micro.
Summary: The Final Decision
Choosing the right Sidelok doesn’t have to be complicated. Identify your optic’s footprint from the list above, determine your preferred co-witness height, and experience the most advanced mounting system on the market.
Ready to upgrade your mounting solution? Shop the Full Sidelok Collection Here
See the whole list of compatible optics – Download the Full Compatibility Chart
