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Geissele Automatics Super Modular
California Proposition 65 Warning

This product can expose you to chemicals including lead, known to cause cancer and birth defects. For more info visit P65Warnings.ca.gov.

Geissele Automatics

Super Modular

$375.00
Available California compliant

Geissele Automatics MK4, Super Modular Rail, Handguard, 13.5", M-LOK, Barrel Nut Wrench Sold Separately (GEI-02-243), Gas Block Not Included, Desert Dirt Color, Product Finishes, Shade Variations and Other Imperfections Are Normal Due to the Manufacturing Process 05-278S

Key Details
Brand Geissele Automatics
Manufacturer Part Number 05-278S
UPC 854014005724
SKU GEI05-278S
Current Stock 26 available
Quantity Updated Apr 24, 2026 8:15 PM
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Purchase Requirements
  • Final availability is confirmed at checkout.
In-Store Pickup Required: All firearm purchases must be picked up at our Beverly Hills location after background check completion.
Product Description

The Super Modular Rail (SMR) MK4 M-LOK is Geissele's ultra-lightweight M-LOK handguard option. These rails are purpose-built and feature integrated short M1913 picatinny rail sections at the fore of the rail in the 3, 6, and 9 o'clock positions. Maximum venting for heat dissipation also dramatically reduces the rail's overall weight, while maintaining its same strong and rigid platform. It utilizes Magpul's M-LOK technology at the 3, 6, and 9 o'clock positions, as well as the upper 45 quadrants. The SMR MK4 is both versatile and modular, allowing the user to tailor their platform to his or her unique needs. The SMR MK4 also features Geissele's proprietary 2.25" long barrel nut. This increases the surface contact where the rail interfaces with the receiver and creates a platform that can be trusted to be straight and true the entire length of the free float rail. This increases accuracy and zero repeatability during disassembly and reassembly when performing maintenance. Requires a Geissele barrel nut wrench for installation (sold separately).

Features
  • Height: 2.4 "
  • Inner Diameter: 1.35 "
  • Outer Diameter: 2.11 "
  • Weight w/ Hardware: 13.5oz.
  • Length 13.5";Includes Barrel Nut (Barrel Nut Wrench Sold Separately)"
  • Geissele Automatics AR-15 13.5 Super Modular Rail MK4 M-LOK"
Specifications
UPC: 854014005724
Manufacturer: Geissele Automatics
Manufacturer Part #: 05-278S
Model: Super Modular
Model (Alt): MK4
Size: 13.5"
Type: Handguard