Summer Cleanout Sale!
Huge Savings On 2000+ Items From 200+ Brands - SHOP NOW

Daily Deal: Remington Stripped Stainless 1911 Slide ~~$329.99~~ $109.99 - Get Yours!

13.5" Super Modular Rail MK4 M-LOK Black

MK4 10.5" M-LOK Super Modular Rail Black

GEISSELE AUTOMATICS LLC - AR-15/M16 MK 4 SUPER MODULAR RAILS, M-LOK

12 Reviews

Color

Black
DDC

Item Length (Inches)

9.300
13.500
15.000
10.500

Brownells #

100015365, 100015366, 100017389, 100018960

MFR #

05-283B, 05-278B, 05-315B, 05-283S

UPC

854014005694, 854014005717, 854014005731, 854014005700

$300.00 - $375.00

Purchase Limit

Select Items In Stock

NOTIFY ME WHEN IT'S BACK IN STOCK

Can we ship this to you? (US only)

How To Buy Guns Online

International purchase information

What is the GEISSELE AUTOMATICS LLC - AR-15/M16 MK 4 SUPER MODULAR RAILS, M-LOK?

The Super Modular Rail MK4 M-LOK™ is Geissele’s ultra-lightweight M-LOK option. These rails are purpose-built and feature integrated 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 rails overall weight, while maintaining its same strong and rigid platform.

The MK4 M-LOK rail features M-LOK slots at the 3, 6 and 9 o’clock positions as well as the upper 45° quadrants. This allows the user to keep the weight on the rail system down, while keeping the modularity and versatility to attach accessories as necessary. Barrel nut wrench & gas block not included.

See all of our AR15s and AR15 parts here.

Available options

Image	Description
	9.3" Super Modular Rail MK4 M-LOK BLK UPC: 854014005694
	13.5" Super Modular Rail MK4 M-LOK Black UPC: 854014005717
	Mk 4 15" M-LOK Super Modular Rail, BLK UPC: 854014005731
	MK4 9.3" M-LOK Super Modualr Rail DDC UPC: 854014005700
	MK4 13.5" M-LOK Super Modular Rail DDC UPC: 854014005724
	MK4 10.5" M-LOK Super Modular Rail Black UPC: 810081130097
	MK4 10.5" M-LOK Super Modular Rail DDC UPC: 810081130080

Please select a FFL Dealer

7 dealers near

No dealers found

Please search by another zipcode to find the nearest dealer.

Brownells Retail Store

You must select required check box

Note:

Listed hours & fees are not guaranteed and subject to change. Please contact the dealer to confirm current hours & fees.

* Must accept required fields.

Brownells Featured Dealers

Choosing a Brownells Featured Dealer is the fastest and easiest way to complete your purchase. Brownells Featured Dealers have agreed to perform FFL transfers on guns purchased online from Brownells. We have their necessary FFL information on file and your FFL order will ship directly to them once processed.
Standard Dealers

Standard Dealers have not yet agreed to perform FFL transfers on guns purchased online from Brownells. If you choose a Standard Dealer, you are responsible for contacting that dealer and arranging for the dealer to submit a signed copy of an FFL and to give Brownells permission to ship the gun.
Not Available Dealers

Not Available Dealers are dealers Brownells cannot ship guns to at this time. These dealers either do not meet our requirements for FFL transfers, or prefer to not perform transfers for guns purchased online from Brownells.

7 dealers near

Alternative products

Add on

AR-15/M16 MK 4 SUPER MODULAR RAILS, M-LOK REVIEWS

4.9

12 Reviews

5 Stars

92%

4 Stars

3 Stars

2 Stars

1 Stars

Reviews Summary

The AR-15/M16 MK 4 SUPER MODULAR RAILS, M-LOK receives high praise for its quality, fit, and ease of installation, appealing to users who value solid construction. Some concerns arise from discrepancies in product appearance versus what's advertised, and there are mixed experiences with customer service regarding returns. Overall, it's a recommended product for building a sturdy rifle.

What Reviewers Are Saying

Product Quality

75%

Reviewers consistently highlight the excellent quality of the MK 4 SUPER MODULAR RAILS. Many note its sturdy build, solid fitment, and ease of installation, making it an attractive choice for those seeking durability and reliability.

Fit and Design

70%

The fit and finish of the rail gain positive comments, with users appreciating the compatibility with various rifle builds. Although some note variations in color, overall satisfaction with design features remains high.

Customer Service

40%

Customer service observations are mixed, with reports of swift responses to inquiries but also instances of incorrect items being sent. While many had a satisfactory experience, a few highlighted issues during returns.

Delivery Experience

60%

Many reviews commend quick shipping and delivery, contributing positively to the customer experience. However, some buyers experienced discrepancies in item reception, which affected overall satisfaction.

Overall Satisfaction

80%

Overall, customers express strong satisfaction with the product, often recommending it for its quality and performance. Despite a few minor issues reported, the consensus is that it’s a worthwhile purchase for AR-15/M16 builds.

Customer Photos & Videos

Sort by Filter by rating

Nothing beats a Geiselle

Actually the first time I bought a Geiselle Automatics hand guard. Used to use Midest Industries who makes some really great stuff, but I got very disgusted with their sales policies and dealer assistance. So i just bought this as a retail purchase. I will never buy any other handgaurds now except a Geiselle. Oustanding quality and the best barrel nut you will ever see. 2.5" long and provides unmatched stability and anti flex characteristics to your rifle. A+++ rating. This handguard went on a .300 Blackout Short Barrel Machine Gun. Best gun I have ever built. A couple other Geiselle Automatics components are in the gun too.

Would you recommend this? Yes, I would recommend to a friend

by GARRY FAEGENBURG on December 18, 2025

Verified Purchase

Was this review helpful? 0

awesome handguard in every way.

I had zero doubts that id be disappointed in this rail. Quality and ease of installment was 5 stars. Fitment is perfect, 5 stars. The size of this barrel nut is huge and solid! I believe that is what makes this setup so solid. Ima quad rail guy, specifically Daniel Defense, I think they're the best, but if you need or want m-lok this is the way to go. You'd haft to hit this thing extremely hard to cause your attachments to go offline. Read the instructions just to make sure you dont over tighten things! As usual I have zero complaints about Brownells. Fast shipment and excellent communication.

Would you recommend this? Yes, I would recommend to a friend

by Frank on March 08, 2025

Verified Purchase

Was this review helpful? 2

Excellent

Looks, feels and fits great on light contour 20 inch rifle. Sturdier than M Lock for bipod or light mounts on the side and bottom without feeling front heavy .

by Larry Lange on October 30, 2023

Verified Purchase

Was this review helpful? 1

Geissele MK4 Rail

Excellent quality

by MARLON MARTINEZ on September 10, 2023

Verified Purchase

Was this review helpful? 0

Beautiful hand guard and bombproof design

I am not an acolyte of any particular brand, but this hand guard did not disappoint me one iota. Fit and finish was excellent. Barrel nut and hand guard retention design are excellent. It has a little more weight than some other hand guards but I don't mind that for my needs. Best tip I can give someone else is not to use this with a milled upper receiver, it is designed to fit most forged receivers. I really am satisfied with this product and will buy it again.

by ANDREW SMITH on September 08, 2023

Verified Purchase

Was this review helpful? 1

View All 12 Reviews

Customer Questions

0 Questions

GEISSELE AUTOMATICS LLC - AR-15/M16 MK 4 SUPER MODULAR RAILS, M-LOK

Add To Favorite

Pin in Brownells Featured Dealers

Pin in Standard Dealers

Pin in Not Available Dealers

AR-15/M16 MK 4 SUPER MODULAR RAILS, M-LOK REVIEWS

Brownells Featured Dealers

Standard Dealers

Not Available Dealers