BAKFlip MX4 vs Undercover Armor Flex

Welcome, truck enthusiasts and aficionados alike, to the thrilling world of tonneau covers!

Just when you thought these truck accessories were all about hiding your truck bed goodies from curious passersby, let’s flip that script – they’re also your secret weapon for a more aerodynamic ride. Oh, and did we mention the bonus feature?

They’re like a little wind whisperer for your truck, nudging it along with less air resistance and squeezing out that extra mile per gallon.

Here the Armor Flex is a great option when it comes to trifolds. It features unique signature design and is the 2nd famous choice in UnderCover tonneaus.

Here the BAKflip MX4, is also an equally famous cover, which is their top of the line. But which of these two trifolds is for you?

Well, to answer this, we have to dig into their designs.

Now, buckle up, as we’re about to navigate through the maze of tonneau terrains. On one side, we have the illustrious Armor Flex – think of it as the silver medalist sprinter in the UnderCover tonneau Olympics.

It flaunts its quirky design like a peacock spreading its feathers, just waiting to be admired.

On the flip side, the BAKflip MX4 is playing in the big leagues. Now, you might be scratching your head, wondering, “Which of these magnificent tri-folds should grace my truck?”

Well, strap in, as we’re about to embark on a riveting rollercoaster ride through their blueprints. Let’s uncover their unique perks, and all details that might just make you fall head over heels for one of these gems. All aboard!

Design Overview

UnderCover Armor Flex
Undercover Armor Flex

Stepping into the ring first, we have the high-end contender, Armor Flex. Unlike its rival, the BAKflip MX4, this beauty sports robust aluminum panels from nose to tail. But Armor Flex didn’t just stop at premium materials – they’ve given their cover a serious style upgrade.

How, you ask? By pre-coating each cover with a dashing Line X finish. Now, for those not in the know, Line X is a spray-on armor for your truck. It’s like giving your cover a superhero cape that fights off wear and tear.

But here’s the kicker – adding this protective coating in the aftermarket would send your wallet on a diet, costing you five to ten times more than the initial price.

With Armor Flex, you get this extra defense built in from the get-go. What’s not to love about that?

Undercover armor flex
Line X coating of Undercover Armor Flex

Now, here’s the cherry on top – the Armor Flex, with its already souped-up design, doesn’t cost an arm and a leg. Surprisingly, it’s even easier on the wallet than the Bakflip MX4. How’s that for a bonus?

But wait, there’s more. Armor Flex has seriously leveled up its sealing game, especially compared to its previous version. Imagine a watertight cocoon surrounding your truck bed – with a three-lip sealing all around, including along the tailgate, your cargo will be as dry as the Sahara.

And, oh, the latches! They’ve got slam latches and dual tailgate action latches that are a breeze to operate. Plus, to prevent any unwanted friction, they’ve thoughtfully equipped the cover with rubber shoes. No more cover scuffles or scratch woes.

But we’re not finished yet! You see, the Armor Flex cover is a stickler for position, too. With the help of prop rods, you can securely fasten it at 2/3rds or in the last position. Talk about functional finesse!

Now, let’s shift gears and steer towards the BAKflip MX4. Much like its counterpart, it can confidently hold its own in both the 2/3rds and the last positions, flaunting buckle straps and rods respectively.

However, here’s where we start to see the MX4 take a different road. In its final position, it snuggles against your truck with rubber shoes, so it’s okay to lean some hefty cargo against it – your truck won’t get so much as a scratch.

Plus, it leaves your 3rd brake light in clear sight, unlike the Armor Flex which plays a full-on cover-up.

Automatic latches? Both the MX4 and Armor Flex have them. But, in a twist of design, the MX4 skips out on dual tailgate action sealing.

This means, if your tailgate’s open and you try to close the cover, you’re going to have a bit of a situation. It’s like trying to close the front door with the back door wide open.

If you’re a multitasking maestro and switch between covers often, you might just forget about this quirk. And before you know it, you’ve created a wee bit of a security hiccup.

Diving into the composition, the MX4 ditches pure aluminum for an aluminum composite. But don’t let that fool you – these panels are as sturdy as they come, with a protective layer of fiber-reinforced polymer (FRP) thrown into the mix.

It’s like equipping your truck with an extra layer of resilience!

BAKflip MX4
FRP coating of BAKflip MX4

The cover also weighs less (just 50 lbs of the packed box compared to Armor Flex’s 80 lbs).

Both covers have EPDM rubber seals, and along with this, comes 2 drain tubes which are connected with the side rails where the bed rests on.

Protection & Durability of these covers:

Both of these covers are equally durable and can carry 400 lbs of evenly distributed weight.

Undercover armor flex installed
Armor Flex inner rails.

Both have unique coating as well. In case of Armor Flex with its Line X coating, it protects the cover against dents, scraps, scratches… and of course UV rays, so the cover does not fade too quickly and in summer things stay cooler underneath.

With water-tight seals and a draining system, both covers are good in sorts of weather, but with Armor Flex’s 3 lip sealing along the tailgate provides better overall protection.

In case of BAKflip MX4, the cover is prone to leakage under the tailgate area.

But still it also provides you with good enough sealing.

And both provide almost equal sealing on sideways.

Both have seals outside which prevent water from going in, and any water that does leak in goes and accumulates in the drain tube along the rails.

Another seal sits between that rail and the truck’s bed and it doesn’t allow the water to leak from those drain pipes, and water simply evacuates from the tubes, that you may have to install by drilling.

Also no cover is 100% waterproof, and there is always a little bit of leakage. That’s why they don’t market any with “water-proof” and instead its always “water resistant”.

One thing I really like about BAKflip MX4 is that the cover comes with rubber pads, which when open rests against the rear of your truck.

On the other side, the Undercover Armor Flex does not come with any rubber pads, and on the last open position the cover simply stands exactly at 90 degrees, so you can’t just lean them against your cabin.

And its prop rods are not strong enough to hold any heavy cargo as well.

Another good thing about BAKflip here is that with FRP coating, it gives better protection against UV resistance.

But the cover lacks in performance.

Which has the better Performance?

BAKflip MX4
BAKflip MX4 installation

Both covers have a very similar mechanism of operation. There are cable latches, on either sides, and you pull and fold the panels to open them up.

And you can secure in 2/3rd with buckle straps and last position with prop rods.

But overall, the operation seems more smoother in BAKflip (just a little bit).

Note: With time, the MX4 starts absorbing water in them, and the panels starts getting heavier and heavier and so in the long run, Armor Flex would be more smoother in operation, maybe that’s why this cover has 5 years warranty, where the MX4 has 2.

FYI: One thing I liked a lot about this Armor Flex is that it contains a skid-resistant surface for improved traction when loading or unloading heavy cargo. No slips, no falls, just smooth moves, and cool grooves.


When it comes to security, the Under-cover Armor flex and the Bakflip MX4 are two of the best truck bed covers on the market. They both offer a high level of security.

Still, there are some critical differences between the two that you should know before purchasing.

Undercover armor flex installation
Undercover armor flex before installation

The Armor Flex is made from lightweight aluminum that is incredibly strong and durable.

Armor Flex features a weatherproof design, so you can rest assured knowing to be protected no matter what kind of weather.

The Bakflip MX4 is also made from high-quality materials but heavier than the Under-cover Armor flex.

It is not waterproof or weatherproof, so you’ll need to keep that in mind if you live in an area where weather can be unpredictable.

Both the Under-cover Armor flex and the Bakflip MX4 offer a high level of security.

Still, the Under-cover Armor Flex takes it a step further with its waterproof and weatherproof design.

If you’re looking for the a great “secured” truck bed cover on the market, then the Under-cover Armor Flex is the way to go. Watch this video.

Ease of Use

The Under-cover Armor Flex has a standard sleeper style headboard. It also has a drop-in aluminum bed rail system that helps make loading and unloading trucks quick and easy.

Armor Flex ease of use
Armor Flex ease of use

This truck bed cover is lined with impact-resistant composite material, resisting scratches and dents.

This truck bed cover also contains a skid-resistant surface for improved traction when loading or unloading heavy cargo.

The BakFlip MX4 series is a hard folding cover. This truck bed cover has an all-steel construction, making it durable and long-lasting.

It also has a matte black powder coat finish for a sleek look. The hinge system on this truck bed cover is concealed, which gives it a clean appearance when it’s closed.

The BakFlip MX4 series can be opened with one hand, making it easy to use.

Plus, the tailgate lock ensures that your cargo will remain safe while you are on the go.

While both of these truck bed covers are great options, the Under-cover Armor flex may be the best choice for someone who is looking for an easy-to-use model.

This truck bed cover is simple to operate and contains features that make it resistant to scratches and dents.

Plus, the skid-resistant surface provides improved traction when loading or unloading cargo.

So what’s the verdict?

Well, both covers are good enough when it comes to trifolds.

But the Undercover Armor Flex, is a cheaper option and comes with dual action tail gate seal, Line X coating, and better overall sealing.

On the other side, the BAKFlip MX4 gives you better UV protection with its FRP coating.

But the biggest selling point for me (in case of BAKflip) is always their customer service. It’s simply one of the best. And I would buy the cover for that reason.

Otherwise, you can go with Armor Flex.

PS. The price difference between this and the Ultra Flex is under 50 bucks, last time I checked, so that cover with better features can be considered as well.