For a beginner, figuring out the differences between a Romeo X, a Romeo RS, a Romeo 1 Pro and the rest can be hard. That’s why we’ve brought together this guide breaking down the SIG Romeo sight family.
SIG Romeo Pistol Sight Line-up at a Glance
Romeo Zero – Entry-level polymer red dot sight for range toys and beginner setups.
Romeo 1 Pro – A mid-tier workhorse optic with a large window and solid performance, though it’s less durable than premium options.
Romeo 2 – A modular, high-end red dot for duty use that can convert from an open to a closed emitter.
Romeo M17 – A durable, military-spec enclosed emitter optic with great NV performance but compatible with specific M17/M18 slides only.
Romeo X Pro – A modern, durable all-metal open- and closed-emitter optic series praised for its low profile.
Romeo X Compact – Smaller, scaled-down versions of the X Pro for micro-compact carry pistols.
Romeo RS Pro – A budget-friendly successor to the Romeo Zero, featuring a more robust hybrid polymer/steel design.
Romeo RS Compact – The compact version of the RS Pro for smaller carry pistols.
SIG Romeo Pistol Optics
Romeo Zero
Entry-level polymer red dot sight for range toys and beginner setups. Discontinued.
The Romeo Zero is widely considered a budget-tier option best suited for range toys (and you often see it bundled with the P365 and P322). Early versions had a polymer housing and lens, which keeps the weight down and the price low, but the controls are frustrating – the button is right next to the lens, meaning you’ll smudge the glass every time you adjust brightness. The Elite version added a metal shroud.
Specs:
- Footprint: RMSc
- Window size: 24mm
- Height: 0.93 in (23.7 mm)
- Emitter: Open
- Battery Type: CR1632
- Battery Life: ~20,000 hours
- Reticle Options: 3 MOA or 6 MOA dot
- Reticle Colors: Red
- Waterproof Rating: IPX4 (splash resistant, not submersible)
- Brightness Settings: 8 DL (no NV settings)
- Additional Features: Polymer housing, integrated rear sight notch.
Romeo 1 Pro
A mid-tier workhorse optic with a large window and solid performance, though it’s less durable than premium options.
For years, this was the standard “nice” SIG optic. It was designed to fit the P320 and M17 slides right out of the box. It offers a large, clear window and holds zero reliably. While it lacks the ruggedness of newer models, many users have gotten years of reliable service from it. The metal shroud was almost mandatory for CCW. It remains a solid, if slightly dated, choice.
Specs:
- Footprint: DPP
- Window size: 30mm
- Height: 27.4 mm
- Emitter: Open
- Battery Type: CR1632
- Battery Life: ~20,000 hours
- Reticle Options: 3 MOA or 6 MOA dot
- Reticle Colors: Red
- Waterproof Rating: IPX7 (submersible up to 1m)
- Brightness Settings: 10 DL / 2 NV
- Additional Features: Top-load battery, optional steel shroud available.
Romeo 2
A modular, high-end red dot for duty use that can convert from an open to a closed emitter.
The Romeo2 is a modular system built for duty use. You can run it as an open emitter, or slap on a polycarbonate shroud and rear lens to effectively turn it into a closed emitter optic. It is incredibly durable and has great specs, but it’s bulky, expensive, and a bit complicated to set up.
Specs:
- Footprint: DPP
- Window size: 30mm
- Height: 27.45mm
- Emitter: Modular (Open/Closed)
- Battery Type: CR2032
- Battery Life: ~25,000 hours at medium setting
- Reticle Options: 3 MOA, 6 MOA, or Circle Dot
- Reticle Colors: Red
- Waterproof Rating: IPX7
- Brightness Settings: 12 DL / 3 NV
- Additional Features: Modular shroud system (open/closed configs), MagnetAC (magnetic activation)
Romeo M17
A durable, military-spec enclosed emitter optic with great NV performance but compatible with specific M17/M18 slides only.
This is a military-spec, fully enclosed optic designed for the US Army’s M17/M18 pistols. It’s built like a tank and features an innovative mounting system. The biggest catch is its proprietary footprint, which only fits on military-spec M17/M18 slides or specific civilian slides. It sits incredibly low, allowing you to use standard-height iron sights. For those with the right pistol, it’s a top-tier performer, especially under night vision.
Specs:
- Footprint: SIG-LOC (M17/M18 MHS & Commem.)
- Window size: 24mm
- Height: 27.94mm
- Emitter: Closed
- Battery Type: CR2032
- Battery Life: ~50,000 hours (dot only)
- Reticle Options: Circle Dot
- Reticle Colors: Red
- Waterproof Rating: IPX7 (Gas purged)
- Brightness Settings: 12 DL / 3 NV
- Additional Features: Fully enclosed emitter, FDE/Coyote color, Integrated gas deflector
Romeo X Series
A modern, durable all-metal open- and closed-emitter optic series praised for its low profile.
The Romeo X line is SIG’s current flagship, built for duty and carry. They finally moved away from the Romeo 1 Pro design and built something rugged with 7075 aluminum housing. All variants feature IPX7 waterproof ratings and night-vision compatible brightness settings. Sights sit super low on the slide, meaning you can usually co-witness your standard iron sights without needing tall “suppressor height” sights.
Romeo X Pro
Inspired by the Romeo M17, Romeo X Pro was designed for full-size pistols like the P320. It’s a rugged, reliable open-emitter optic praised for the clear glass, intuitive controls, and extremely low deck. The circle-dot reticle ensures fast target acquisition and gives more versatility with your reticle options for the task. The battery is easy to replace without removing the optic. Available with a red or green reticle color.
- Footprint: DPP
- Window size: 24mm
- Height: 0.94 in [23.88 mm]
- Emitter: Open
- Battery Type: CR1632 (Side load)
- Battery Life: ~20,000 hours on medium brightness with dot only
- Reticle Options: 2 MOA, 6 MOA, Circle Dot (2 MOA dot / 32 MOA circle)
- Reticle Colors: Red or Green
- Waterproof Rating: IPX7
- Brightness Settings: 12 DL / 3 NV
- Additional Features: Integrated fiber optic rear sight, MOTAC
Romeo X Pro Enclosed
Exactly the same as the standard Pro, but with a hood covering the emitter. This keeps rain, lint, and carbon buildup from blocking your reticle. The optic performs exceptionally well under night vision use. The only minor trade-off versus the open X Pro is the slightly reduced window size, though this doesn’t meaningfully impact shooting performance or target acquisition speed.
- Footprint: DPP
- Emitter: Enclosed
- Additional Features: Fully enclosed system, nitrogen purged, MOTAC
Romeo X Pro Sig Loc
This is the enclosed Pro model, but it uses the proprietary Sig Lock footprint for enhanced rigidity. Only buy this if your slide has the matching cuts.
- Footprint: Sig Loc Pro
- Emitter: Enclosed
- Additional Features: Same specs as Enclosed Pro, just with the specialized mounting interface.
Romeo X Compact
This is the little brother, designed for micro-compacts like the P365, Hellcat, or Glock 43X. Fits the RMSc footprint. The red dot packs all the durability and features of the Pro into a smaller package, making it a perfect fit for concealed carry pistols without adding bulk.
- Footprint: RMSc
- Window size: 24mm
- Height: 0.94 in [23.88 mm]
- Emitter: Open
- Battery Type: CR1632
- Battery Life: ~20,000 hours on medium brightness with dot only
- Reticle Options: 2 MOA, 6 MOA, Circle Dot (2 MOA dot / 32 MOA circle)
- Reticle Colors: Red or Green
- Waterproof Rating: IPX7
- Brightness Settings: 12 DL / 3 NV
- Additional Features: Integrated rear sight, very low deck height.
Romeo X Compact Enclosed
The ultimate micro-compact carry optic. It combines the small footprint of the Compact with the bomb-proof reliability of an enclosed emitter. It’s one of the few closed-emitter optics that mounts directly to an RMSc footprint (like a Glock 43X or Hellcat) without an adapter plate. Competitors like the Holosun EPS Carry usually require a plate, which raises the optic height.
- Footprint: RMSc
- Emitter: Enclosed
- Additional Features: Fully enclosed, same specs as standard Romeo X Compact.
Romeo X Compact Sig Loc
The enclosed compact optic with the proprietary locking lugs for P365 slides that support it.
- Footprint: Sig Loc Compact
- Emitter: Enclosed
- Additional Features: Maximum mounting security for small carry guns.
Romeo RS Series
A budget-friendly successor to the Romeo Zero, featuring a more robust hybrid polymer/steel design.
The RS series is SIG’s latest effort to create a high-quality, budget-friendly optic that learns from the mistakes of the Romeo Zero. These pistol sights use a “hybrid” construction – a steel skeleton inside a polymer housing. It’s not as bomb-proof as the X series, but it’s significantly cheaper and tougher than the old plastic ones. Note that these are open emitters only; no enclosed options here.
Romeo RS Pro
The budget option for full-size pistols. It offers a crisp dot, improved controls, side-loading battery, and reliable performance at a price point below the Romeo X series. The main trade-offs are a lower waterproof rating (IPX4), no NV settings, and a slightly taller deck height, which means you’ll likely need suppressor-height sights to co-witness. Also, the unit has a single button for brightness adjustment.
- Footprint: DPP
- Window size: 31mm
- Height: 1.21 in [30.7 mm]
- Emitter: Open
- Battery Type: CR1632 (Side load)
- Battery Life: ~20,000 hours on medium brightness
- Reticle Options: 2 MOA, 6 MOA, Circle Dot (2 MOA dot / 32 MOA circle – available in red color only as of the date of this post)
- Reticle Colors: Red or Green
- Waterproof Rating: IPX4 (Splash resistant)
- Brightness Settings: 8 DL
- Additional Features: Hybrid steel/polymer construction.
Romeo RS Compact
This is the compact version for smaller pistols. It offers the same features and build philosophy as the RS Pro but with the RMSc footprint.
- Footprint: RMSc
- Emitter: Open
- Other Specs: Identical to the Romeo RS Pro
Getting to Know SIG Romeo Sight Family
Here are some things that will help you navigate SIG Sauer Romeo pistol red dot series:
Technologies & General Design Concept
MOTAC (Motion Activated Illumination): You know this as “shake awake” (a standard popularized by Holosun). The optic powers up when it senses movement and shuts down when it’s still to save battery life.
Manual Brightness Only: Unlike some competitors (Trijicon RMR and Holosun), SIG optics don’t feature automatic brightness adjustments or solar panels. However, many prefer manual brightness control to avoid the lag common in auto-brightness red dots.
Emitter Type: SIG pistol optics come in open emitter or closed emitter designs. Open emitters – Romeo-X Pro, Romeo-X Compact, Romeo-RS, Romeo Zero, Romeo1 Pro – are common, but the diode that projects the dot is exposed to the elements. Closed emitters – Romeo-X Enclosed Compact, Romeo-X Enclosed Pro, Romeo2, Romeo-M17 – seal the diode behind a second pane of glass, protecting it from elements.
Reticle Options: Most current SIG optics give you a choice between a simple dot (3 or 6 MOA) and a “Circle-Dot” reticle (a 32 MOA ring with a 2 MOA center dot).
Battery: Most modern Romeo sights feature a side-loading battery tray and use the CR1632 battery.
Housing: Materials range from Weapons-Grade polymer on budget models to tough 7075 T6 aluminum on the higher-end X series.
Footprint: You are generally looking at either the Delta Point Pro (DPP) footprint for full-size guns (like the P320/M17) or the RMSc footprint for carry guns (like the P365/Hellcat).
SIG LOC: SIG recently introduced a proprietary SIG LOC footprint. This offers extra mounting rigidity for specific SIG slides, but it kills compatibility with other guns. It’s great if you are married to the platform, but limiting if you want to swap optics around.
SIG Romeo Pistol Sight vs. Competition
Direct Mounting: Newer Romeo models have popular optics footprints and mount directly to SIG pistols and other optics-ready guns without requiring additional plates.
Battery Life & Solar Panels: While 20,000 hours is decent, it’s not industry-leading. Competitors like Holosun often push 50,000 hours and include solar fail-safes.
Price vs. Value: SIG optics tend to be a bit pricier than Holosun for similar specs, but they often look better on SIG pistols and offer that seamless co-witness capability that generic brands struggle to match.
Lens Quality: Professionals consistently highlight that SIG Romeo optics deliver excellent glass clarity with minimal distortion and tint, particularly the newer models.
Low Deck Height: The Romeo X sights sit allows you to co-witness with standard-height iron sights on P320s without needing suppressor-height sights.
Warranty and Customer Service: SIG provides excellent warranty support and responsive customer service, with multiple professionals reporting fast replacements and straightforward warranty resolution. The warranty covers life of electronics and body.
