4BROS FN RaceCar Appendix Rig – IWB Sidecar Holster for FN Pistols

Built for comfort, concealment, and adaptability. The 4BROS FN RaceCar Appendix Rig is an IWB (Inside Waistband) appendix sidecar holster system designed specifically for popular FN concealed carry pistols. Featuring adjustable sidecar spacing, a flexible injection-molded adapter system, and customizable ride height and cant adjustments, the RaceCar Appendix Rig is engineered to improve comfort, reduce printing, and provide a more natural fit for everyday concealed carry.

Designed for Comfortable Appendix Carry

The 4BROS RaceCar Injection-Molded Appendix Adapter Plate is engineered to flex and articulate with the body's natural contours and movement. This flexibility helps reduce common pressure points associated with appendix carry while allowing the holster to conform more naturally against the body for enhanced concealment and long-term comfort.

Quick Overview

Flexible 4BROS RaceCar Injection-Molded Appendix Adapter Plate
Adjustable spacing between the holster and the magazine carrier
Adjustable cant and ride height for both holster and mag carrier
Designed to improve comfort during seated carry and daily movement
Compatible with red dot optics and suppressor-height sights
Retention indexed on supported weapon-mounted lights
Made in the USA

Equipped with Discreet Carry Concepts 1 Series Overhooks and a Modwing concealment wing, the RaceCar Appendix Rig is designed to provide a secure connection to the belt while helping rotate the pistol grip closer to the body for improved concealment and reduced printing.

Information on the belt attachments used for the 4BROS RaceCar Appendix Rigs can be found through our Inside Waistband Attachments Blog article.

Unlike traditional fixed sidecar holsters that can feel rigid during daily carry, the RaceCar Appendix Rig utilizes a flexible 4BROS RaceCar Injection-Molded Appendix Adapter Plate that connects the holster and magazine carrier. This articulated design allows the system to flex naturally with the body while helping improve comfort, concealment, and mobility throughout daily movement, seated carry, and extended wear.

Key Features

4BROS RaceCar Injection-Molded Appendix Adapter Plate – Lightweight, durable, and engineered to provide flexibility without sacrificing support. The adapter plate twists and articulates with the natural angles and curves of the body to improve comfort and concealment during appendix carry.
Adjustable Sidecar Spacing – Customize the distance between the holster and magazine carrier to optimize concealment, comfort, and carry positioning for different body types and carry preferences.
Adjustable Cant & Ride Height – Fine-tune the draw angle and carry height of the holster to improve concealment, reduce firearm printing, and establish a consistent draw stroke.
Adjustable Magazine Carrier Height & Cant – Customize the magazine carrier's ride height and angle to improve accessibility, comfort, and concealment.
Optimized for Daily Carry – Designed to reduce hot spots and pressure points commonly associated with appendix carry while maintaining stability during movement, seated carry, and extended wear.
Below-the-Beltline Bridge Design – The connection point between the holster and magazine carrier is positioned below the beltline to improve concealment, reduce rigidity across the beltline, and allow the system to flex more naturally with the body during movement and seated carry.
Retention on the Light (Light-Bearing Models) – Compatible weapon-mounted light configurations provide secure retention, repeatable indexing, and consistent draw performance.
Precision Molded Fitment – Each holster is custom-formed to the exact firearm and weapon light combination selected to ensure proper retention, clearance, and reliability.
Optics Ready Design – Compatible with most popular pistol-mounted red dot optics commonly used on Smith & Wesson pistols.
Suppressor Height Sight Compatible – Compatible with most standard and suppressor-height iron sights used on modern defensive pistols.

Information on available holster color options is available in our Holster Colors Guide.

View additional compatible appendix carry options in the 4BROS RaceCar Appendix Rig Collection.

Precision Fitment for FN Pistols

Pistol Fitment: Each holster is precision-formed to the exact Smith & Wesson pistol or pistol/light combination selected from the dropdown menu to ensure proper fit and retention.

Magazine Carrier: The included magazine carrier is matched to your selected firearm platform and features adjustable retention through a side-mounted tension screw.

Optics Compatibility: The holster profile is cut to clear most popular pistol-mounted red dot optics used on Smith & Wesson pistols.

Supported FN Pistols

The 4BROS Smith & Wesson RaceCar Appendix Rig is available for several popular Smith & Wesson concealed carry pistols. Each holster is precision-molded to the exact firearm or firearm and weapon light combination selected from the dropdown menu to ensure proper fit and retention.

FN Reflex
FN Reflex XL

Supported Weapon Light Configurations

Light-bearing RaceCar Appendix Rig models retain on the weapon-mounted light instead of the pistol frame. This allows consistent retention and repeatable indexing across supported firearm and light combinations.

FN Reflex + Streamlight TLR-7 Sub
FN Reflex XL + Streamlight TLR-7 Sub

Compatible lights available from Four Brothers:

Streamlight TLR-7 HL-X Sub USB, Part# 69503 can be purchased from us HERE.

Made in the USA

The 4BROS FN RaceCar Appendix Rig is proudly manufactured in Logansport, Indiana using premium materials, precision CNC-cut components, and purpose-built forming processes.

Pro Tip: Apply a removable thread locker to all hardware screws after final adjustment to help prevent loosening over time.

Frequently Asked Questions

What is the 4BROS FN RaceCar Appendix Rig?

The RaceCar Appendix Rig is an IWB (Inside Waistband) sidecar-style appendix holster designed specifically for FN pistols. It features adjustable spacing between the holster and magazine carrier for improved comfort, concealment, and customization.

What makes the RaceCar Appendix Rig different from traditional sidecar holsters?

Unlike fixed sidecar designs, the RaceCar Appendix Rig uses a flexible 4BROS RaceCar Injection-Molded Appendix Adapter Plate that allows the holster and magazine carrier to move naturally with the body. This improves comfort during movement, seated carry, and extended daily wear.

What pistols and lights does this holster support?

The RaceCar Appendix Rig supports several popular FN pistol and weapon light combinations listed in the supported fitment section above. Each holster is custom-built for the selected configuration to ensure proper fit and retention.

How does retention work?

For light-bearing configurations, retention is indexed on the weapon-mounted light. Non-light-bearing models retain directly on the firearm. Magazine retention is adjustable using the side-mounted tension screw.

Is the holster adjustable?

Yes. Both the holster and magazine carrier feature adjustable cant and ride height. The spacing between the components is also adjustable to help optimize comfort and concealment.

Will this holster work with red dot optics?

Yes. The holster profile is designed to clear most popular pistol-mounted red dot optics commonly used on FN pistols.

What if my FN configuration is not listed?

If your pistol or weapon light configuration is not shown, contact the 4BROS holster support team. Additional configurations may already be supported or under evaluation.

FN Holsters

4BROS FN RaceCar Appendix Rig