BAKFlip MX4 vs BAK Revolver X4s: Hard Fold or Hard Roll-Up?

The BAKFlip MX4 and the BAK Revolver X4s are the two covers most F-150, Ram and Silverado owners end up choosing between once they’ve decided on a premium hard cover. They come from the same maker, share a 400 lb rating, a 5-year warranty and no-drill installs, and both latch automatically and lean on your tailgate lock. The difference is how they open: the MX4 folds toward the cab, the X4s rolls up into a drum.

We haven’t tested either cover ourselves. This comparison uses BAK’s specs (from Amazon and the retailer etrailer), the Amazon listings we checked on November 12, 2026, and Car and Driver’s hands-on test of the X4s. Where a test result appears, we say who ran it.

The short answer

Buy the BAKFlip MX4 unless you specifically want a roll-up. It opens the whole bed by standing upright behind the cab, it has the larger owner base, and it costs about $300 less on the most popular fitment. Buy the Revolver X4s if you’d rather roll the cover out of the way than fold panels, want BAK’s slash-resistant slats, or carry long loads that a standing stack would get in the way of.

Spec by spec

Prices for the same trucks

Both lines are sold per truck and bed. These are the Amazon prices we saw on November 12, 2026, for the same fitments:

On every truck we checked, the MX4 was cheaper by about $180 to $330. Prices move often, so check both listings for your truck: MX4 price, X4s price.

Bed access: folding up vs rolling up

Both covers claim 100% bed access, and both let you drive fully open, but the way they get there differs.

The MX4 folds forward in sections and then stands the folded stack upright on prop rods behind the cab. That frees nearly the whole bed for tall cargo, but the standing panels block the rear window while they’re up.

The X4s rolls its slats into a drum at the cab end and straps it there. BAK says it doesn’t block the rear window or factory cameras. Car and Driver’s experience differed: on its long-term 2024 Ford Maverick, the coiled cover “significantly” affected rear visibility, because the drum is thicker than a soft roll. The Maverick’s short bed and low cab make that worse than it would be on a full-size truck.

Our bed access calculator estimates the drum takes 12–15 in at the cab end for tall cargo (BAK doesn’t publish a figure), while the floor stays clear.

Security

Neither cover has its own key. The MX4’s automatic latches engage as each panel closes, and the X4s’s rear slat locks to both rails with slam latches; on both, the releases sit inside the bed, so a locked tailgate is what keeps them shut. On our three-level security scale both are level 2.

BAK markets the X4s as slash-resistant and “Level-3” on its own scale, and the interlocking aluminum slats are harder to cut than a vinyl-skinned folder’s seams. If someone gets the tailgate open, though, both covers open too. If your tailgate doesn’t lock, see the tailgate locks on our accessories page, or look at keyed covers in the most secure tonneau covers.

Weather sealing

The X4s is the only one of the two with an independent water test. Car and Driver said it’s “not completely weatherproof, but it’s close,” with only a small amount of water in the bed and along the edges after exposure to the elements. BAK says its flush side seals and beveled edges shed water without drain tubes.

The MX4 uses edge-to-edge rubber seals and a built-in drainage system with drain tubes, so route the tubes through the bed’s drain holes when you install it. We found no independent water test of the MX4.

Neither cover is waterproof in the strict sense, and no cover we track is; see are tonneau covers waterproof?

Installation

BAK claims a one-person install in under 30 minutes for the MX4 and a 10-minute clamp-on install for the X4s. Car and Driver’s X4s install took about an hour and a half. The testers found the rail knobs stiff and the adhesive seal backing hard to peel, and said the cover needed a lot of adjusting to fit well; they called it easier with two people. Owners on etrailer also report the X4s rolling stiffly in cold, wet weather. Our install guide covers the general steps.

Bed racks and rooftop tents

For a rack that bolts to the cover rails, buy the T-slot versions: the MX4 TS or the Revolver X4ts. With the standard versions, etrailer reports:

• The TruXedo Elevate rack fits the MX4.
• The Thule TracRac SR works with the X4s, with possible slight rubbing at the uprights, but can interfere with the MX4’s seals.
• The Yakima OverHaul HD isn’t compatible with the X4s, which lacks T-slots.

More options are in tonneau covers with a bed rack.

Owner track record

The MX4 has by far the larger owner base on Amazon: 763 ratings averaging 4.2 on the F-150 5.5 ft listing, 1,839 on the Silverado listing and 1,285 on the Ram. The X4s had 160 ratings averaging 4.5 on the F-150 listing. Both have long histories, and BAK has updated the MX4 recently (a 2025 Zach Attack Customs review calls the current version Gen 3, and 2026 Amazon listings add an EZ-Lift version).

Day-to-day use

The two covers ask different things of you every time you open the bed. With the MX4 you release the latches, fold the panels forward one at a time and, if you need the whole bed, lift the stack onto its prop rods. Folding covers let you open just the rear section for a quick grocery run. With the X4s you pull the release, roll the cover forward and strap the drum at the cab; Car and Driver said it takes a decent yank on the cord to unlatch, but rolls up seamlessly after that. Car and Driver also noted the X4s can be closed with the tailgate up.

Which should you buy?

• Most owners: the MX4. Same rating, same warranty and full access for about $300 less on the F-150.
• You want to see out the back with the cover open on a full-size truck, or you hate folding panels: the X4s rolls rather than folds, though Car and Driver found the drum still hurt visibility on a small truck.
• Slash resistance matters: the X4s’s aluminum slats.
• You’re on a tighter budget: the BAKFlip G2 keeps the fold-to-the-cab design for a little less, or see Gator EFX vs BAKFlip G2.

Not sure a hard cover is the right type? The cover matcher ranks every line we track against how you use your bed, and tri-fold vs roll-up vs retractable explains the trade-offs by type.