BAKFlip MX4 and Undercover Ultra Flex are known as Low-profile Hard Folding Covers. Like the MX4 the Ultra Flex is made from aluminum making it lighter than polycarbonate or thermoplastic covers. This makes it easy to handle. It has one of the lowest profiles of any tonneau cover on the market giving it a sleek look while maintaining its strength.
BAK Industries BakFlip MX4
To open the truck cover you must pull the cable underneath the panel on either side, which activates the pull cable release mechanism. So you can lower the tailgate, pull the cable.
BAKFlip MX4
Tri-Fold Tonneau Cover
- Quick and easy, complete bed access
- Safely drive with the cover in 2/3 or fully open
- No drilling needed
- The durable EPDM rubber seals
- Enhanced end caps for the mounting rails
- Multi-function tailgate seal
- Drain tubes included
And then in a matter of seconds, you’re going to be able to access your full bed by just lifting up each panel and you don’t have to do it on that side. It can be on this side too. This cover flips up to give you full-bed access, which is very nice. When you need to haul up most of your bed, it can be propped up while you’re driving and you can go highway speed with this cover safely leaning against the back window.
The BAKFlip also offers a compatible storage box called a BackBox 2, which is a folding toolbox that clamps onto the side of the truck. The MX4 has rails that we clamp onto the side and a drain tube, which keeps the water out of the bed. If you undo this knob at the bottom, the whole cover can be removed in a matter of seconds, the rails will stay on. And these hooks just snap, lower the cover, strap it here and drive with it in place.
UnderCover Ultra Flex
Also, notice the lashes at each fold keeping the Ultra Flexes seal nice and tight and the profile low. To drive with the cover open simply secure the snap straps to hold it in place. The Ultra Flex can fully fold and stand on the end allowing for maximum use of the truck bed and it doesn’t lean against the truck’s rear glass. Many people like this feature.
- Constructed of aluminum panels
- Matte black powder coat finish
- EPDM seals provide maximum water resistance
- Holds up to 400lbs of evenly distributed weight
- Installs with no drilling
- Integrated rail light included
- Operates from either side with slam latches
- Dual action tailgate seal
- Easy installs
- little leaks of water
Unlike the MX4 the Ultra Flex also comes with LED strip lighting. This makes loading and unloading gear a snap at night. You’re gaining truck luggage that goes on the side of the bed and you get these LED light strips that Mount to the side of the rail. So it’s a good little feature to have.
Unlike other tonneau covers, this cover has an integrated tailgate seal, which does not require you to shut the tailgate prior to shutting the cover. You can do either of them first. So pull the cable, fold it up. The Ultra Flex is also getting a little bit more bang for your buck.
Construction and Durability
The materials used and overall construction quality is important for longevity and durability when exposed to various weather conditions.
| Ultra Flex | MX4 | |
|---|---|---|
| Materials | Aluminum panels with a polymer honeycomb core | Aluminum panels reinforced with composite materials |
| Industrial grade vinyl cover | Relies solely on the aluminum skin for protection | |
| Underside coating for additional durability | Provides rigid strength | |
| Provides rigid strength | ||
| Weatherproofing | Coats all seams and joints with thick weather stripping | Minimal seal coverage |
| Minimizes water intrusion | More susceptible to water intrusion | |
| Effective in heavy rain | May leak around perimeter edges in heavy rain | |
| Longevity and Warranty | Impressive lifetime warranty | 3-year warranty |
| Owners report lasting over 10 years in harsh climates | May start having issues after 4-5 years | |
| Shows confidence in long-term durability | – |
Security and Protection
The locking mechanisms and theft deterrence capabilities also differentiate the two covers.
| Ultra Flex | MX4 | |
|---|---|---|
| Locking Features | Dual locking rods operated from both sides | Single side latching |
| Smart locks for added security | Locks can be disabled more easily | |
| Cover can’t be opened or removed when locked | ||
| Ability to Secure Cargo | Completely seals off the bed | Leaves gaps at the front and rear of the bed |
| Secures gear inside the bed | Less effective in securing gear inside | |
| Valuables are safer when the truck is unattended | Less secure against theft | |
| Theft Deterrence | Locking mechanism and vinyl encapsulated design | Exposed aluminum design |
| Better prevents theft of cover and cargo | Easier target for thieves |
Access and Convenience
The speed and ease of opening and closing the covers is another important consideration for owners.
| Ultra Flex | MX4 | |
|---|---|---|
| Ease of Opening/Closing | Panels fold smoothly and quietly | Hinges are stiffer and louder |
| Gas spring assisted operation | Requires removing a cumbersome prop rod | |
| Pull strap for easy closure | ||
| Folding Mechanism | Panels fold flush against the cab when open | Panels fold back towards the tailgate |
| Panels fold out of the way for full bed access | Panels must be fully removed for maximum clearance | |
| Bed Access with Cover Closed | Ability to fold the first panel back while keeping the rest closed | Must be fully opened for bed access |
| Allows quick access to part of the bed | No partial opening capability |
Appearance and Style
Aesthetics and customization options also influence which cover is more desirable.
| Ultra Flex | MX4 | |
|---|---|---|
| Color/Finish Options | 8 different color options | Standard black finish |
| Various finishes, including gloss and matte | Limited to black color | |
| Ability to color match with the truck | No color-matching options | |
| Low Profile Design | Sits nearly flush with truck bed rails | Slightly thicker profile |
| Better matches the contours of the cab | Slightly less integrated appearance | |
| Visual Appeal | Sleek, rounded profile with clean seam lines | More industrial, utilitarian look |
| Modern and premium style | May not appeal aesthetically to all owners |
Price and Value
Budget is often the deciding factor so cost comparison between models is key.
| Aspect | Ultra Flex | MX4 |
|---|---|---|
| Retail Cost Comparison | Base retail price: $1100 | $850 |
| Commands a 30% premium over the MX4 | Lower initial investment | |
| Cost Per Year of Use | Amortized cost over 10 years: $110/year | Amortized cost over 10 years: $85/year |
| Marginal annual difference | Lower annual cost | |
| Value for Money | Justifies higher price with better quality materials, construction, and lifespan | May offer lower upfront cost |
| Better warranty, protection, and resale value | May not have the same long-term value |
Compatibility and Fit
The covers must properly fit various truck makes, models and bed configurations.
| Ultra Flex | MX4 | |
|---|---|---|
| Truck Model Compatibility | Fits GM, Ford, Toyota, Nissan, and Ram trucks | Also fits GM, Ford, Toyota, Nissan, and Ram trucks |
| Universally compatible with these makes | Universally compatible with these makes | |
| Compatible with 5′ 7″ or 6′ 6″ truck bed lengths | Compatible with 5′ 7″ or 6′ 6″ truck bed lengths | |
| Adjustability/Customization | Mounting rails can be adjusted along the bed sides | Fixed position rails |
| Can be trimmed down if needed | No ability to customize the length | |
| Bed Rail Clearance | Low profile clamps clear bed rail caps and accessories | Clamps are thicker |
| No-drill installation | Mounting bolts may require drilling into caps or interfere with accessories |
Additional Features
Useful extras and options further differentiate the models.
| Aspect | Ultra Flex | MX4 |
|---|---|---|
| LED Light Strip | Available as an upgrade for integrated LED cargo lights | Not offered |
| Operated by wireless remote | ||
| Adds convenience and visibility in low light conditions | ||
| Drain Tubes | Included drain tubes channel water off the cover | No drainage ability |
| Prevents moisture from pooling and dripping into the bed interior | ||
| Gas Struts | Equipped with robust gas struts | Standard torsion springs require more physical effort and frequent adjustment |
| Provides smooth and effortless operation when opening/closing | Requires more manual effort |
Conclusion and Recommendation
Evaluating all factors and testimonials, a definitive verdict on which of these quality tonneau covers rises above can be made.
Summary of Key Differences
- Superior weatherproofing, security, access, style and longevity make the Ultra Flex stand out.
- MX4 competes on price but falls short on construction quality and features.
Situations Suited for Each Cover
- Demanding owners who prioritize quality and function should opt for the Ultra Flex.
- Budget conscious buyers willing to compromise on some aspects can save money with the MX4.
Final Verdict
The UnderCover Ultra Flex is the clear winner when comparing all attributes side by side with the BAKFlip MX4. The Ultra Flex justifies its higher price tag by offering a tonneau cover built to last with useful features that enhance convenience and versatility. Owners seeking the best combination of form and function will appreciate the advantages only the Ultra Flex provides.
So both the MX4 and the Ultra Flex are made by a company called Truck Hero. BAK Industries MX4 has a three-year warranty. UnderCover has a five-year warranty. So you’re getting a longer warranty with the Ultra Flex. Both of these are going to be good hard folding covers that give you full-bed access. It’s all a matter of preference if you like the lighter finish which matches the bed caps well or you want to go for that darker stealth look. Both of them are American-made and of high quality.