In-Depth Review: Undercover Ultra Flex Cover

Do you want to massively upgrade the appearance of your truck without sacrificing useability? The Undercover Ultra Flex tonneau cover is a great accessory that can be easily installed by the DIYer. It offers an easy installation, weatherproofing, and a matte black finish that compliments every truck.

Primary Features

  • Aircraft-grade aluminum panels
  • No-drill installation
  • Weathersealed
  • Multi-position folding cover

Competing products

  • BAK BAKFlip G2
  • Gator FX
  • Rough Country Tri-Fold Tonneau Cover

What We Like

  • Aircraft-grade aluminum panels are lightweight and durable
  • Incredibly simple installation
  • Finished underside for a factory appearance

What We Don’t Like

  • Cost is higher than many competitors
  • Aluminum panels have some sharp edges
  • Awkward to remove once installed without help


Design Features


The Undercover Flex tonneau cover is made of aircraft-grade aluminum panels and rails. The panels feature weatherstripping between each folding panel to ensure a watertight seal. A drip rail channels water away from the bed to prevent contents getting wet.

Most tonneau cover companies use fiberglass or some other similar material. While these materials are well-known for lightweight properties, durability is not a strong suit. Aluminum, on the other hand, provides a highly durable surface that can take a thrashing without bending or breaking.


The Undercover Flex uses a matte-finish black paint that is bonded to the aluminum panels. This coating provides a huge amount of durability and fade resistance. The Undercover Flex will keep it’s correct matte finish for many years, even in hot, dry climates where it is exposed to the sun constantly.

Fade resistance is only one part of the benefit of aluminum. Aluminum is non-ferrous, so it does not rust, no matter how wet and humid the weather is. Fiberglass panels will eventually degrade in humid and wet environments and will show signs of buckling and warping. Covers that use fiberglass panels similar to the Undercover Flex often exhibit problems with weatherstripping seals after a few years of use. This does not happen with the Undercover Flex. The aluminum panels prevent distortion, even after many years of constant use in less than ideal climates.

Undercover has applied a BedRug coating to the bottom of the Ultra Flex cover. This coating provides a soft surface and a factory-finished appearance and is a crucial detail most competitors skip.

Opening and Closing, and Use While Driving

Multiple operating positions provide superior access for owners. Undercover advertises that the Ultra Flex may be opened fully, partially open, or fully closed while driving. When fully open, the cover sits lower than the competition. The cab-side rail is a mere six inches, unlike competitors models that can exceed a foot of lost space!

Among the most important features, the L-Rail connectors are a real advantage over competitor products. The rails are installed without drilling holes, preventing the damage that always happens when holes are drilled in a truck bed. Not only do the L-Rail connectors prevent unnecessary damage, they also make it incredibly easy to remove the cover when needed.

Locking it Up

Dual deadbolt locks are integrated into the rail. These highly durable locks prevent unauthorized access to the contents of your truck bed and keep your truck secure. Because the locks act against the side rails, the tailgate can still be opened and closed as normal. Even owners of trucks with automatic tailgates can use the Undercover Flex tonneau cover.

Light it Up

Most of the Undercover Ultra Flex competitors either offer a light kit as an option or provide a mostly useless, dim light. The Ultra Flex comes with a factory LED light strip for illuminating your bed in the darkness. The light makes it much easier to find what you need without having to open the cover all the way.

Racks and Accessories

The cover sits far enough inside the rails of your truck to allow a utility rack to be installed while still allowing the Undercover Flex to be opened and closed as normal. Some users found that the Undercover Flex tonneau cover rubbed against some racks, and other reviewers comment that care must be used when installing a rack to ensure adequate clearance.


Undercover offers a full five-year warranty on the Ultra Flex cover. Undercover really stands behind their product, too. Many reviewers that experienced issues with the Ultra Flex cover received a replacement from the company free of charge.

Installing the Undercover Flex

The Undercover Flex weighs in at a hair over 70 lbs, so it isn’t exactly lightweight. However, installation is easy because the individual components are not heavy. One person can easily install the Undercover Flex in an afternoon. This is because of the overall design of the cover. Because the rails are clamped in place rather than bolted down, installation is much more straight-forward than competitor models. Aligning and leveling the cover is simple, even when installing alone.

Using the Undercover Flex

A key feature of the Undercover Flex is the versatility it offers. Most covers must be either fully open or fully closed when driving. The Undercover Flex can be partially open when driving, allowing owners greater flexibility.

The panels move easily along the rails and lock into place securely. Rubber bumpers prevent the panels from touching. When fully open, all but the last few inches of the bed is accessible. The cover folds upright, but remains several inches from the rear window of the truck. This prevents damage to the cover or the cab when driving.

How Water Resistant is the Undercover Ultra Flex?

When closed, the Undercover Flex provides a water resistant seal. Youtuber Gear Runner demonstrated how well the Undercover Ultra Flex prevents water from easily getting into the bed in an online video.

Gear Runner demonstrates that the Ultra Flex does a very good job at preventing water from getting into the bed. Using a high-pressure wash wand at a car wash, Gear Runner was able to get a small amount of water to penetrate the seals, but no standing water accumulated in the bed of his truck. Gear Runner told his audience the cover has seen some torrential rain without leaking nearly as much as he was able to get by using the high-pressure wand.

Most users report that the Undercover Ultra Flex is among the best on the market for preventing leaks. Some users also report that failed seals within the warranty period were quickly handled by Ultracover and free replacements were provided to users that reported failing seals.

The matte black finish has a factory-correct appearance, and the textured surface underneath the cover gives the entire product a high-end look and feel.

Users reported no issues loading and unloading equipment from the bed of a truck with the Undercover Flex installed.


A tonneau cover is an expensive product and no one wants to throw money away o n an inferior product. Truck owners that buy the Undercover Flex are happy with the purchase. Amazon reviewers rate the Undercover Flex at 4.1 of 5 stars.

The aluminum panels offer better security and durability than fiberglass panels. Owners in regions where hail is common report that the panels will show hail damage. In some cases, owners report that the evidence of hail damage is worse on the Undercover Flex than on covers with fiberglass panels. Truck owners in hot, humid, and arid environments found the aluminum Undercover Flex tonneau cover to be more durable than competitors.

The tonneau covers durability is made even better by the cleverly designed water seals. The seals and drains prevent standing water and keep your gear dry, even when going through a car wash. Many users found the Ultra Flex seals to work better than competitors.

The Undercover Flex is a top-of-the-line tonneau cover that is backed by top-notch customer service and an extensive 5-year manufacturers warranty. The Made in the USA cover is available for most truck beds.

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