Holster Design and Fitment Guide

 

 

Holster Design & Fitment Guide

This page explains how our holsters are designed, why fitment is exact, and how to choose the right setup the first time. If you’re unsure about a specific configuration, reach out before ordering—we’d rather help you choose correctly than have you end up with the wrong holster.

How retention works on light-bearing holsters

Many holsters clamp primarily on the firearm. Our light-bearing holsters are different: the mounted weapon light is the retention device. That means the holster is engineered around the light’s shape and geometry to create a consistent “click-in” fit.

  • Retention is on the light: draw feel and security are consistent across slide lengths that share the same light fitment.
  • Exact light model required: close is not close enough—tiny differences change retention and safety.
  • Light must be installed: if the light is removed, the holster will not retain the pistol properly.

Rule of thumb: If your product description says “retention is on the light,” then the holster requires that light to be mounted.

Why the exact light model matters

Lights that look similar can be different where it counts: rail keys, bezel length, switch housings, body width, and mounting position. Because retention is built around those exact surfaces, swapping to a “similar” light can change retention, draw feel, or prevent the pistol from seating fully.

  • Same brand ≠ same fit: a light “family” is not automatically compatible across variants.
  • Same name ≠ same geometry: “HL,” “HL-X,” “Sub,” and “1913” versions can differ significantly.
  • Mounting position matters: the same light mounted differently on different rails can change fitment.

Firearm variations & fitment reality

Firearm “family names” can hide important differences. Frame size, rail geometry, dust cover shape, trigger guard profile, optic cut, and aftermarket modules can all affect holster compatibility—especially on precision-fit Kydex.

Common fitment breakers

  • Rail differences: accessory rails are not standardized across all models, even within a brand.
  • Aftermarket frames/modules: grip modules and frames can change key dimensions and light position.
  • Optics and irons: tall sights and certain optic footprints may require specific clearance.
  • “Almost the same gun”: similar slide lengths or names don’t guarantee the same holster fit.

Tight tolerances: intentional by design

Our holsters are built for secure retention and a consistent draw. That requires tight tolerances. We prioritize performance and safety over a loose, “soft” fit.

  • Security first: a duty-ready holster should not feel sloppy or unstable.
  • Consistency: repeatable presentation matters for training, range work, and competition.
  • Fit is by configuration: exact firearm + exact light + intended carry method.

Reality: A holster can be safe and secure, or it can be loose and forgiving. We choose safe and secure.

Wear marks & finish expectations

Holsters involve contact between Kydex and your firearm/light. That contact can produce cosmetic wear over time—especially on high points and contact surfaces. This is normal and expected with any securely-retained holster.

What to expect

  • Cosmetic wear on common contact areas (high points, edges, and controls).
  • Wear that increases with training volume, grit/debris, and repeated draws.
  • Different finishes wear differently—some show marks sooner than others.

IWB vs OWB: how to choose

The right choice depends on your goal: concealment, comfort, access, duty use, or competition speed. Here’s how to decide quickly.

Inside the Waistband (IWB)

Best for concealment. Designed to pull the grip inward and reduce printing.

Not ideal if:

  • You want fast on/off carry without a proper belt system.
  • You prefer maximum comfort with larger setups (big lights/compensators).
  • You’re primarily using the holster for duty or competition.

Outside the Waistband (OWB)

Best for training, range, duty, and competition. Typically faster access and more comfort.

Not ideal if:

  • You need deep concealment under light clothing.
  • You expect the holster to disappear under a t-shirt without layering.
  • You don’t use a rigid belt that supports OWB carry.

Belt attachments: what to pick

Attachments change how the holster rides, how stable it feels, and how easy it is to take on/off. If you’re on the fence, choose based on your daily routine (work belt, gym shorts, frequent removal, etc.).

Attachment Best For Requires Belt? Strength Tradeoff
DCC Monoblock Everyday carry with a belt Yes Very secure & stable Less “quick on/off” than clips designed for fast removal
UltiClip / Ultituck No-belt carry or variable clothing No (can be used with a belt too) Very versatile Placement matters more for comfort and stability
Soft loops Maximum security with belt carry Yes Extremely secure Slowest on/off
OWB loops / duty-style mounts Training, range, duty, competition Yes Stability + access Less concealment than IWB

Want the full breakdown? These guides go deeper on each carry style and attachment type:

Choosing a color/pattern? This guide can help: Holster Colors .

Common wrong assumptions that cause fitment issues

  • “Same brand light = same holster fit.” Not true. Model variants can differ where retention happens.
  • “If it’s close, it will work.” Not with precision-fit Kydex. Close often means unsafe or inconsistent retention.
  • “I can remove the light later.” Not on light-bearing holsters—retention is designed around the light.
  • “A holster should never leave marks.” Normal use can create cosmetic wear on contact surfaces.
  • “Same gun family means same holster.” Rails, frames, and modules can vary and break compatibility.

Order-the-right-holster checklist

  1. Confirm your exact firearm model (include generation, MOS/OR versions, and rail type when applicable).
  2. Confirm your exact weapon light model (include “Sub,” “1913,” “Glock,” and model variants).
  3. Confirm your carry style (IWB vs OWB, concealment vs training/duty/competition).
  4. Choose the right belt attachment based on your clothing and how often you take the holster on/off.
  5. Read the “not compatible” notes on the product page before ordering.
  6. If anything is unclear, contact us with your exact firearm + light model before purchase.

FAQ

Do light-bearing holsters work without the light attached?

No. If retention is on the light, the holster requires the light to be installed to function properly and safely.

Why won’t a “similar” light fit?

Small changes in light geometry (keys, housings, bezels, switches, and mounting position) can change retention and seating. Our holsters are built around the exact model listed on the product page.

Will my holster scratch my firearm?

Cosmetic wear can occur on contact surfaces with normal use, especially with training volume and debris. Keeping the holster and firearm/light clean reduces friction and wear.

Do different slide lengths fit the same light-bearing holster?

Sometimes. Because retention is on the light, certain configurations may share compatible fitment, but you should always follow the exact firearm list on the product page. If your model isn’t listed, ask before ordering.

What’s the easiest way to avoid ordering the wrong holster?

Match your exact firearm model and exact light model to the product description, then confirm IWB vs OWB and your belt attachment choice. If anything is unclear, contact us with your setup before placing the order.

Still not sure? Reach out with your exact firearm model, exact light model, and whether you want IWB or OWB. We’re happy to help you choose the right holster the first time.

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Let customers speak for us

from 4642 reviews
Sig Sauer P365-XMACRO & TLR-8 Sub IWB Holster (MACRO)
Damon Watts
Awesome holster

Awesome holster, I went with 4bros because they made a holster for my Gun/optic and Light/laser combo. I loved how I was able to make choices and customize my holster when I ordered. My gun fits awesome and I been wearing it daily, I’m an auto detailer and I put it to the test the other day. I wore joggers and wore the gun In the holster in my appendix all day even while I was inside cars vacuuming and cleaning. Honestly I forgot I was wearing it most the day. The wing helps a lot and I love the clip on it.

Sig Sauer P365-XMACRO & TLR-8 Sub IWB Holster (MACRO)
4BROS Springfield Armory Echelon RaceCar Appendix Rig
Jeremy
I really like the fitment and how quick i was able to get my holster for my echelon with the tlr7x

I really like the fitment and how quick i was able to get my holster for my echelon with the tlr7x . The metal clips are a nice touch, super sturdy holds tight. Having the adjustability on the mag holster angle is nice . Comfier then other brands like my trex arms side car, where the extended mag is more upright. And I like the fact that I can take that extension bracket off for the mag holster and just run the gun holster if need be. Great holster, huge adjustability, ordered and shiped quick. 5 out of 5 stars for sure

4BROS Springfield Armory Echelon RaceCar Appendix Rig
Glock 43X or 48 MOS & TLR-8 Sub IWB Holster
Erik McDaniel
The holster was heavy duty.

The holster was heavy duty. It seemed like quality build. . The fit and finish was perfect for my glock43x with tlr8 and NDZ threadless compensator fit great.

Glock 43X or 48 MOS & TLR-8 Sub IWB Holster
Sig Sauer P365-FUSE IWB Holster
Curtis Moore
This is the second holster I have bought from 4Bros

This is the second holster I have bought from 4Bros. This one was for a P365 Fuse and I love it. But here is the great part. I have a P365 Tacops. I installed a Ramjet with after burner. Wich now makes my gun the same length as the Fuse. It works perfectly!!! It is a straight match for match.

Sig Sauer P365-FUSE IWB Holster
Springfield Hellcat Pro with 1913 TLR-7 Sub IWB Holster
Jay Details
Hellcat Pro Comp 15 rounds with tlr7 H Sub fit

Hellcat Pro Comp 15 rounds with tlr7 H Sub fit perfectly in holster i like i can loosen it to my liking and color perfect

Springfield Hellcat Pro with 1913 TLR-7 Sub IWB Holster
4BROS Kimber 2K11 RaceCar Appendix Rig
Zaxary Massaro
Me likey a lot

Me likey a lot.. so does my kimber. Shipment got delayed but that’s okay. Product is A+

4BROS Kimber 2K11 RaceCar Appendix Rig
4BROS Sig Sauer P211 RaceCar Appendix Rig
C.Y.
Top Notch

I've worn this holster through several dynamic range training sessions as well as a few small local USPSA matches. This is without a doubt the BEST sidecar-style holster I've ever used. It stays put on the belt even through all the running around, etc. Retention is excellent with that positive "click," and combined with a quality belt, it holds/distributes the weight of my P211 GT4 with the 17-round mag+1 and a spare 23-round mag very well. It also conceals exceptionally well even while carrying a chonky gun like the GT4. Drawing the firearm and spare mag is very smooth and quick.

In addition to all the things listed above, this is easily the most comfortable AIWB rig I've ever used. I've worn it literally for 8+ hours with no hotspots, soreness, etc by the end of the day. IMO, this beats T1C, T Rex Arms, and other well-known sidecar-style appendix rigs with little to no effort.

Kudos to Four Brothers for the awesome craftsmanship and quick shipping! The only reason this received five stars is because I couldn't give it six!

4BROS Sig Sauer P211 RaceCar Appendix Rig
Staccato HD P4X & TLR-1 HL Duty & Competition Holster
Bud Newton
Awesome holster and perfect fit

Awesome holster and perfect fit. Easy draw yet good retention. Couldn’t be happier!!

Staccato HD P4X & TLR-1 HL Duty & Competition Holster
4BROS Staccato RaceCar Appendix Rig
Joel Sosa
I am truly impressed by the quality of these holsters

I am truly impressed by the quality of these holsters, I bought two of them for different weapons. and I really appreciated the speed of the shipping. I ordered them on the night of August 31st and received them on September 5th. It’s impressive; I can say they are number one in the industry. I’ve bought holsters from many different companies, and they all take a long time to ship.

4BROS Staccato RaceCar Appendix Rig
Kimber DS Warrior OWB Holster
Christian Mariani
Fits 6"

It fits the 6 inch warrior, although it leaves the muzzle exposed obviously. Good quality holster for outdoor use. I wrapped mine (poorly) in 500D cordura. Wish they made one for the long slide.

Kimber DS Warrior OWB Holster
Ruger RXM IWB Holster
Chayton Nez
5 stars because I have tested every RXM holster

5 stars because I have tested every RXM holster. 4bros is the best fit. 1 down side is the monoblock clip is one notch higher than the missing. This articulation causes the holster to ride outward. Drilling an extra hole above greatly resets the position making this perfect!

Ruger RXM IWB Holster
4BROS Glock RaceCar Appendix Rig
Mark Pulford
Awesome holster

Awesome holster. It's my second one. Can't say enough about this company. They make fantastic products all day long. Keep up the great work.

4BROS Glock RaceCar Appendix Rig
P365-XMACRO IWB Magazine Carrier (MACRO)
Dwight Richmond
10 out of 10 zero complaints! Awesome product

10 out of 10 zero complaints! Awesome product.

P365-XMACRO IWB Magazine Carrier (MACRO)
Streamlight TLR-7 HL-X Sub USB
Anonymous
TLR-7 SUB.

The light fits the G43X perfectly and as advertised The holster gets purchased on the light not the gun no complaints here on fit.
The light itself was simple to install comes with rechargeable battery which is nice including accessories to charge it and the buttons were customizable and easy to change I'm left-handed and so I switched the paddle so that I can get my trigger finger in from the left side without being interfered with. The features are straightforward once you play with them press and hold and the light comes on as long as you hold press forward once with a click the light stays on. Lumens seem powerful.

Streamlight TLR-7 HL-X Sub USB
Kimber DS Warrior & TLR-1 HL OWB Holster
Jake McDill
Shits fucking sick

Gun fits good and tight like I like em makes me horny

Kimber DS Warrior & TLR-1 HL OWB Holster