Super Modular Rails

Super Modular Rail MK8 M-LOK®

Super Modular Rail MK8 M-LOK®

Super Modular Rail MK8 M-LOK®

MK8 Height:


Available Lengths: 

 7"  •   9.5"  •  13"  •  15"

MK8 ID*:




Installed Weight
(w/ Hardware):

7” MK8 Rail - 8.9oz
9.5” MK8 Rail - 10.6oz
13”  MK8 Rail - 13.3oz
15” MK8 Rail - 14.7oz 

ID* - Inner Diameter
OD* - Outer Diameter
DAQ* - Distance Across Quadrants

Available in Black and DDC

.750" Low Profile Stainless Steel Geissele Super Gas Block Included

Click Here to review our DDC (Desert Dirt Color) disclaimer before purchasing.

NOTE: Our rails are designed to work with Mil-Spec M4 upper receivers. The compatibility with billet receiver sets is unknown.


Item Number:



In stock

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Super Modular Rail MK8 M-LOK®

Full Description

The Super Modular Rail (SMR) MK8 M-LOK™ is Geissele’s ultra-modular model. The SMR MK8 is one of the first rails available to utilize the Magpul M-LOK technology. These rails are designed to give the user full modularity while maintaining a strong and rigid platform. Maximum venting at the lower 45° quadrants create maximum heat dissipation and also dramatically reduces the rail's overall weight. Utilizing Magpul's M-LOK technology at the 3, 6, and 9 o'clock positions, as well as the upper 45° quadrants. The SMR MK8 is both versatile and modular, allowing the user to tailor their platform to his or her unique needs. 

The SMR MK8 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. 

Bundled with a low-profile Geissele Super Gas Block, a $59 value, the SMR MK8 is not only feature packed, but it is also value packed.

Additional Information

Weapon Platform AR15/M4/M16


Installation Instructions

Super Modular Rail MK8 M-LOK®

Reviews (16)

overall rating 5.0

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Rolls Royce of rails - Micah

The most sturdy rail I've ever used without being heavy. If you running something on your rail that requires it to hold zero I would look no further this thing is a tank its not budging anywhere. It also feels very good to grip your hand around the rail.

February 26th, 2019

Greatest rail ever - Ben

This is my second MK8 rail, but first new rail purchased from Geissele. I couldn’t be happier. This will not be my last purchase. And the swag pack is awesome. Love this company.

February 21st, 2019

Work of Art - DMG3

I got the MK8x13” on the 50%off blem sale and Wow what a beautifully machined rail. It’s a lot lighter than expected but built tough and not one blem I could find except on the barrel nut wrench lol. All in all it doesn’t get much better and the swag pack is a plus!

July 15th, 2018

Amazing - Shawn

I put a 15” Blemish model on my DMR build. This thing is freaking awesome. It’s solid so with a bipod the weapon barley moves when I shoot it. Definitely feels like a quality piece of equipment. Also it was a blem but I could not find a single thing that was wrong with it. Geissele you guys have some high standards for your stuff and that says a lot.

February 14th, 2018

Start with the best - Mark

My first AR build, and I could not have picked a better engineered rail. Could probably a bit lighter, but the quality could not be much better. I had to work with a competing rail on a friend's AR and it was a nightmare.

February 8th, 2018

A Product to Impress Pragmatists - Joseph

I've been using the Geissele MK8 13" for a year and a half and the 9.5" for a year at the time of this review. I've been building AR rifles professionally for 3 years now and I have yet to find a rail system/handguard that surpasses the MK8 in any aspect. The installation was super simple, and I love the value that you get with the whole package of rail system, pin-able gas block, AND barrel nut wrench (I despise companies that make you pay extra money for the proprietary barrel nut wrench)!

All in all, there is not a single rail system that I would choose over the MK8, even with the new MK13/14 offerings from Geissele.

January 24th, 2018

Solid well built, definitely good to go - David

Glad I was able to pick this up while on sale! Thanks to the staff for answering my emails and getting my order taken care of. Great quality and craftmanship. I can see why Special Operations choose Geissele. Now I have to order my trigger for my AR pistol build, damn I wish the trigger was still on sale!! lol Thanks again to the staff at Geissele for the swag gifts as well! Happy New Year ( and let me know when the triggers go back on sale lol) I also know Mike (of Garand Thumb fame) and Lucas from T Rex arms love your products.

January 13th, 2018

When Planning this Build, this was the first item decided on - Shwell

I was introduced to Geissele Automatics 4 years ago, and they have been a go to brand ever since. The MK4 Super Modular Rail was the part I designed my latest build around. I am a huge fan of how easily their setup is to install, as well as how resilient it is once installed. The design and execution of this product makes it a great choice for your AR no matter the role. It is strong, and full of great features. MLok is my preferred mounting option, but the full picatinny along the top is a needed feature. The MLok sections are plentiful allowing the user to decide what mounting option works best for them.

Highly Recommend this product. Plinker to Duty, I'd trust this product to perform flawlessly. Rigid, Resilient, and it Looks great.

December 18th, 2017

Perfectly Engineered. - WWSPENCER

You have to feel and see this rail in person to really appreciate the quality. The barrel nut has an extremely flush fit with the rail which makes for a very secure fit. Not only do the include a barrel nut but you get a super low gas block, wrench tool and a swag pack. I highly recommend this product and this company. Excellent customer service as well.

December 17th, 2017

Awesome Rail - Keith

The rail is superb as expected. Only downfall is it does NOT fit the Lantac UAR without some very minor trimming to upper.

December 7th, 2017

Fantastic - Stephen

I first ordered a MK13 and, long story short, ended up with the mk8.
Fantastic rail. Looks great, feels great. Holds true with the barrel but design which locks the rail from any possible movement.
Order one, you won’t regret it.

November 23rd, 2017

Best on the Market - Tyler

As is the usual with Geissele products, whatever they make is the best on the market. Lightweight, strong, stiff (for maintaining zero for lasers/sights on the rail), attractive, offset mounting options, and no more expensive than the competitions' rails (when factoring in the gas block).

I've got one 13" and one 9.5" installed on carbines. If you're on the fence, just do it.

One thing I will say, I would like to see the rails offered without the gas block, for those who already have a gas block, or must use a different gas block for various reasons.

October 30th, 2017

Robust and solid equipment. - David

First Geissele rail I've used, absolutely amazing. The barrel nut design is extremely easy to install. The rail firs snuggly into place. A robust and rigid design that is ergonomic and lightweight. A definite must for the modern AR series of rifles. Could not be happier with my purchase. Had it on my rifle for over five months at the time of this review, still an amazing and robust piece of equipment!

August 28th, 2017

Another excellent product. - Todd

The rail came with every tool needed to install it, as well as a gas block. This is on of, if not the most solid handguards I have used. It drips quality from every pore, is light, and feels wonderful in the hand. Shooting my AR is even more enjoyable and satisfying because of my MK8.

June 13th, 2017

Amazed with the mk8 rail and their customer service! - Zachary

I recently purchased the MK8 13" DDC rail and plan on many more purchases in the future. The rail arrived two days after my purchase, it looks incredible! This rail is perfect, it's strong, light weight, and a breeze to install. During my install I lost a gas block set screw. I contacted Geissele to either buy some more or for a p/n so I could order more else where. Geissele's amazing customer service sent a new set of screws free of charge! I've never been more impressed by a company's product and customer service. Thanks Geissele

June 5th, 2017

Perfection - JP

If your looking for a sleek, sturdy, modular, and great looking rail you have found it. I have the DDC 13" and it's perfect. Easy to install and remove for maintenance on barrel/ Gas block. It comes with a beast of a gas block which once pinned is bomb proof as well as the rail. Great combo. Plus the swag pack is A1 on top of my steak! Much appreciated Geissele.

May 17th, 2017
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