A pistol red dot fits only if its footprint, meaning the pattern of screw holes and recoil bosses on its base, matches the cut in your slide or the adapter plate on it. Most full-size optics-ready pistols take the Trijicon RMR footprint, usually through a plate. Slim slides take the Shield RMSc or Holosun's closely related K footprint. The chart below maps every pistol optic we stock to its footprint, using the makers' own listings.
Use it as a starting point, then confirm against your pistol maker's documentation or the markings on your plate kit. Slide cuts vary by model and generation, and a near-miss footprint is the most common reason an optic won't seat.
Key takeaways
- RMR footprint: Trijicon RMR Type 2, RMR HD, SRO and RCR; Holosun 507C, 407C, 508T and 507COMP; Primary Arms SLx RS-10R.
- Holosun K footprint: 507K, 407K, EPS Carry, RONIN EPS Carry, full-size EPS and SCS Carry. It is close to the RMSc but not identical, so Holosun includes RMSc-to-K or RMR-to-K plates with several of these.
- Shield RMSc footprint, direct: SIG ROMEO-X Compact and Holosun EPS CORE.
- DeltaPoint Pro footprint: SIG ROMEO-X Pro and EOTech EFLX. Aimpoint ACRO: Burris FastFire E. Docter: Burris FastFire 4.
- The Trijicon RCR and RMR HD use the standard RMR footprint, not a dedicated or updated pattern.
Footprint compatibility chart
| Footprint | Optics we stock | Where you'll meet it | Notes |
|---|---|---|---|
| Trijicon RMR | Trijicon RMR Type 2, RMR HD, SRO, RCR (enclosed); Holosun 507C X2/X3, 407C X2/X3, 508T X2, 507COMP; Primary Arms SLx RS-10R | Full-size optics-ready pistols, usually via a plate; RMR offset and rail mounts | The most widely supported pattern. Trijicon's mounting kit lists Glock MOS, Springfield OSP and Prodigy, Walther PDP and H&K VP9. |
| Holosun K | Holosun 507K X2, 407K X2, EPS Carry, RONIN EPS Carry, EPS (full-size), SCS Carry | Slim slides, directly or with Holosun's plate | Holosun ships an RMSc-to-K plate with the EPS Carry and SCS Carry, and an RMR-to-K plate with the full-size EPS. |
| Shield RMSc | SIG ROMEO-X Compact; Holosun EPS CORE | Slim single-stack and micro-compact slides; SIG designs the ROMEO-X Compact for the P365 | Both mount directly to an RMSc cut with no plate. |
| Holosun 509T | Holosun HE509T X2 (enclosed, titanium) | 509T-cut slides; RMR cuts via the included plate | Holosun includes an RMR-to-509T adapter plate. |
| Leupold DeltaPoint Pro | SIG ROMEO-X Pro; EOTech EFLX | DPP-cut slides and plates | SIG and EOTech both list the DPP footprint. |
| Aimpoint ACRO | Burris FastFire E (enclosed) | ACRO-cut slides and plates, ACRO rail mounts | Burris lists the ACRO footprint with a clamp system. |
| Docter | Burris FastFire 4 | Docter-pattern plates and mounts | Burris lists "Docter optic" compatibility. |
| SIG PRO cut | SIG ROMEO1PRO | SIG optics-ready slides with the PRO cut | SIG says it mounts to any pistol with a SIG SAUER PRO slide cut. |
| Pistol-specific | Holosun SCS MOS, SCS P10, SCS PDP, SCS VP9, SCS 320, SCS MP2 | The pistol named in the model | Built to fit one maker's cut directly. Holosun lists the SCS MOS as a direct fit for Glock MOS models. |
RMR footprint: full-size slides
The RMR footprint comes from the Trijicon RMR Type 2, and most of the industry has adopted it. Trijicon launched the sealed Trijicon RCR "with the RMR footprint", designed the RMR HD to fit the same footprint as earlier RMRs, and sells a combined RMR and SRO adapter plate. Holosun lists the Holosun HS507C X2, 407C, 508T and 507COMP as RMR footprint.
On many full-size optics-ready pistols the RMR optic sits on a plate rather than straight on the slide. Trijicon's RMR footprint mounting kit is listed for Glock MOS, Springfield OSP and Prodigy, Walther PDP and H&K VP9 optics-ready slides.
RMSc and Holosun K: slim slides
The RMSc footprint is the narrow pattern for single-stack and micro-compact slides. SIG builds the SIG ROMEO-X Compact on the Shield RMSc footprint for the P365, and Holosun sells the EPS CORE as a direct-mount RMSc sight.
Holosun's K footprint, used on the 507K, 407K and Holosun EPS Carry, is often described as "the same as RMSc". Holosun's own box contents suggest otherwise. The EPS Carry and SCS Carry are listed as K footprint with an RMSc-to-K plate included. If your slide is a plain RMSc cut, expect to use that plate with a K optic, or choose a direct-RMSc sight. Airsoft replica slides follow the same rules, because the optic only sees the cut.
Enclosed footprints: 509T, RCR and the EPS family
A sealed emitter keeps rain, lint and grit off the LED, which matters for anything used outdoors. The enclosed sights we stock don't share one pattern:
- The Holosun HE509T X2 uses its own 509T footprint and comes with an RMR-to-509T plate.
- The Trijicon RCR uses the standard RMR footprint.
- The EPS and EPS Carry use Holosun's K footprint with the plates above, and the EPS CORE mounts directly to RMSc.
- The Burris FastFire E uses the Aimpoint ACRO footprint.
Compare them in enclosed red dot sights, and read enclosed vs open red dots to decide whether sealing is worth it for you.
DeltaPoint Pro, ACRO and Docter
The SIG ROMEO-X Pro and the EOTech EFLX both use the Leupold DeltaPoint Pro footprint. The FastFire E uses the Aimpoint ACRO, and the Burris FastFire 4 uses the Docter pattern. None of these will go on an RMR or RMSc cut without a suitable plate.
Expert tip
Every adapter plate adds height and another pair of screws that can work loose. Where a direct-fit optic exists for your cut, choose it over a plated one. It sits lower, co-witnesses more easily and has one fewer interface to maintain.
How to find your footprint
- Check your pistol maker's documentation, or the markings on the plates in its optics-ready kit.
- Match the plate to the optic. Plates are footprint-specific, and a plate for one pattern will not take another.
- If in doubt, compare the slide cut with the optic maker's footprint drawing. Count the recoil bosses as well as the screw holes.
- Still unsure? Email info@opticstrader.co.uk with your exact pistol model and generation, and we'll help you narrow it down before you order.
New to footprints? Start with our RMR vs RMSc guide. For what to put on the slide once you know the pattern, see best pistol red dot sights and the compact slim-slide red dot guide.
UK note
In England, Wales and Scotland most handguns are prohibited under section 5(1)(aba) of the Firearms Act 1968, which covers any firearm with a barrel under 30 cm or an overall length under 60 cm. In Britain, pistol optics are mainly fitted to airsoft replicas, long-barrelled pistols and pistol-calibre gallery rifles, and by holders of Section 5 authority. Northern Ireland has its own law, the Firearms (Northern Ireland) Order 2004, without an equivalent general ban on short firearms. Confirm your own position with your firearms licensing department.
Frequently asked questions
Which red dot fits a SIG P365?
SIG builds the ROMEO-X Compact on the Shield RMSc footprint for the P365, so it mounts directly. Holosun K-footprint optics such as the EPS Carry come with an RMSc-to-K plate for RMSc-cut slides.
Which red dot fits a Glock MOS, Walther PDP or Springfield Prodigy?
These usually take an RMR-footprint optic through a plate. Trijicon's RMR footprint mounting kit is listed for all three, and Holosun also makes the SCS MOS, which fits Glock MOS slides directly.
Is the Trijicon RMR HD the same footprint as the RMR?
Yes. The RMR HD was designed to fit the same footprint as earlier RMRs. Its body is a different shape, so check it clears your rear sight.
Can I adapt one footprint to another?
Often, with the right plate. Holosun includes RMSc-to-K, RMR-to-K and RMR-to-509T plates with some models. Every plate adds height, so check co-witness with your irons afterwards.
Shop this guide
- RMR Footprint Red Dot Sights — the widest-supported full-size pattern
- RMSc Footprint Red Dot Sights — slim-slide optics, RMSc and Holosun K
- Trijicon RMR Footprint Mounting Kit — RMR-pattern optics on popular optics-ready slides
- Pistol Dot Sights — every pistol optic we stock
