UnderCover Ultra Flex versus the BAKFlip MX4

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.

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

Ultra Flex has a different finish. It’s more of a Satin Smooth Aluminum style. You’ll notice the Ultra Flex is easy to open, simply pull the cable on either side and lift up. A feature that’s really unique to it is its carpeted underside.

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.

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.