UnderCover Ultra Flex specs
| Brand | UnderCover |
|---|---|
| Cover type | Hard folding: Hard folding; stands upright on dual prop rods without resting on the cab |
| Material | Aluminum panels, matte black, carpeted underside |
| Lock | Locks with tailgate. Secured by the locked tailgate. |
| Security level | Level 2: hard, tailgate-locked (our grouping) |
| Bed access | 100% bed access. UnderCover claims 100% bed access: it folds upright on dual prop rods and you can drive closed, partly open or fully open. |
| Drive with it open | Yes |
| Install | No-drill clamp-on install. |
| Load rating | Not published for this listing |
| Weight | 70 lb (listing or retailer figure) |
| Profile | Low profile, at or near the bed rails |
| Weather sealing | Dual-action tailgate seal lets you close the tailgate with the cover up or down. |
| Bed racks | We found no maker-confirmed bed rack pairing for the Ultra Flex. |
| Warranty | 5 yr |
| Made in | USA with global materials (maker claim) |
| Fitment we checked | 2021–2025 Ford F-150 5'7" bed (67.1") (part UX22029) |
| Price tier | $$$ Premium ($900–$1,600), about $1,299.99 for this fitment when checked. See Amazon for today's price. |
- Weight (70 lb) is the Amazon listing's item weight for the F-150 5.5 ft version.
- Siblings: the UnderCover Flex (gloss aluminum, 3-year warranty, about $1,168 for the F-150 5.5 ft, B08L447D51) and the Armor Flex (LINE-X coated panels, about $1,475, B08L42KZV4).
- Fitment years on these listings end at 2025; check the listing's fitment tool for a 2026 truck.
Fitments we checked
Each truck and bed is a separate Amazon listing. Prices are what Amazon showed on November 12, 2026, not live. Always confirm with the listing's fitment tool before you buy.
| Truck and bed | Notes | Price |
|---|---|---|
| Ford F-150 2021–2025, 5'7" bed | Part UX22029 (our representative listing) About $1,299.99 when checked | Check price |
| Ford F-150 2021–2025, 6'7" bed | Part UX22030 About $1,249.99 when checked | Check price |
| Silverado/Sierra 1500 2019–2025, 6'7" bed | Part UX12023; works with MultiPro/Flex tailgates About $1,249.99 when checked | Check price |
| Ram 1500 2019–2025, 6'4" bed with Multi-Function tailgate | Part UX32013; without RamBox About $1,349.99 when checked | Check price |
| Toyota Tacoma 2016–2023, 5' bed | Part UX42014; with or without bedside storage boxes About $1,199.99 when checked | Check price |
| Toyota Tundra 2022–2025, 5'7" bed | Part UX42017; without Trail Special Edition boxes About $1,249.99 when checked | Check price |
| Colorado/Canyon 2023–2025, 5'2" bed | Part UX12029 About $1,199.99 when checked | Check price |
Specs are compiled from maker copy on Amazon and at the retailer etrailer, plus independent tests, and may change between production runs. Not sure of your bed? Use the bed size finder.
UnderCover Ultra Flex Hard Folding Tonneau Cover video review
Video by Ryder in Motion on YouTube. Independent creator content, shown as a reference. It is not part of our scoring.
The UnderCover Ultra Flex is a hard folding tonneau cover with matte-black aluminum panels, a carpeted underside and a fold that stands upright behind the cab. It’s our second-rated hard folder, just behind the BAKFlip MX4. The 2021–2025 Ford F-150 5’7” listing (part UX22029) was $1,299.99 on Amazon on November 12, 2026, and the fitments we checked ranged from $1,199.99 to $1,399.99. We haven’t tested the Ultra Flex ourselves; this review uses the maker copy on Amazon and owner ratings. To compare cover types first, try the cover matcher, or see our best tonneau covers of 2026.
Who the Ultra Flex is for (and who should skip it)
It’s for owners who want a hard folder that opens the whole bed and is flexible in daily use. You can drive in three positions, and the tailgate closes whether the cover is up or down. If you often carry something tall at the front of the bed with the tailgate shut, that seal is a practical advantage.
Skip it if you want the longest track record or a published load rating. The MX4 has far more owner ratings, and BAK publishes a 400 lb rating; the Ultra Flex listing gives none. Skip it if you need a key: like most folders it relies on the tailgate lock.
Security and locking
The Ultra Flex has aluminum panels and locks through your tailgate, which is level 2 on our three security levels. It’s hard enough to stop casual theft, but there’s no separate key. If your tailgate doesn’t lock, fit a Pop & Lock tailgate lock.
Access and everyday use
UnderCover claims 100% bed access. The cover folds upright on dual prop rods without resting on the back of the cab. That should protect the cab paint, though upright panels still block the rear window. The three driving positions (closed, partly closed, fully open) cover most hauling jobs without removing the cover. The bed access calculator shows how an upright stack compares with a standard tri-fold on your bed length.
Weather sealing
The headline feature is the dual-action tailgate seal, which works with the cover up or down. Beyond that, the listing gives no detailed sealing specs, and we found no independent water test of the Ultra Flex. Car and Driver’s tests found that waterproofing a tonneau cover is extremely challenging, and our waterproof guide explains what “water-resistant” means in practice.
Install
It’s a no-drill, clamp-on install. At 70 lb (the F-150 listing’s item weight), it’s easier to place with a second person. Our install guide covers squaring the rails and setting the seals.
Fitment notes
We checked listings for the 2021–2025 F-150 (5’7” and 6’7”), the 2019–2025 Silverado/Sierra 1500 6’7”, the 2019–2025 Ram 1500 6’4” with the Multi-Function tailgate (without RamBox), the 2016–2023 Tacoma 5’, the 2022–2025 Tundra 5’7” and the 2023–2025 Colorado/Canyon 5’2”. Notes:
- Silverado/Sierra: the 6’7” part works with MultiPro/Flex tailgates.
- 2016–2023 Tacoma: the part fits with or without the bedside storage boxes.
- Tundra: the part excludes Trail Special Edition boxes.
- 2026 trucks: fitment years on these listings end at 2025, so check the fitment tool for a 2026 truck.
What you’ll need beyond the box
- A bed mat. The carpeted underside protects cargo from above, not below. A Husky bed mat suits the F-150 5.5 ft bed.
- Cargo control. A cargo net or ratchet straps keep loads put.
- Floor liners, if you’re outfitting a new F-150 SuperCrew: WeatherTech FloorLiners.
See the accessories page for more.
Reliability and warranty
UnderCover gives the Ultra Flex a 5-year warranty and says it’s made in the USA with global materials. The F-150 listing had 46 ratings averaging 4.4, and the Silverado listing 238 at 4.3. That’s a solid record, though smaller than BAK’s. The Flex (3-year warranty) and Armor Flex (LINE-X coating) are siblings if you want to spend less or more.
Bottom line
The Ultra Flex matches the MX4 on what matters day to day: full access, an upright fold, drive-open use and a 5-year warranty. Its tailgate seal that works in either position is a real convenience. It usually costs a little more and publishes no load rating, which is why we rank it just behind. If it’s cheaper than the MX4 for your truck, it’s an equally good buy. Check the Ultra Flex price, or compare all folders in best hard tri-fold tonneau covers.
Accessories that pair with the UnderCover Ultra Flex
Cover care, bed racks, mats and cargo gear sold on Amazon. Most bed and floor products are vehicle-specific: the fitment shown is the listing we checked, so search the same product for your truck if yours differs.
- Bed rackYakima OverHaul HD adjustable truck bed rack (8001151)Works with any cover
Height-adjustable towers with T-slots and SKS locks, rated 500 lb on-road and 300 lb off-road per the listing, for rooftop tents, ladders and boats. The Amazon listing doesn't state tonneau-cover compatibility. Check Yakima's fit guide for your truck and cover before buying.
- Cargo managementKeeper ratcheting cargo bar, 40–70 in (05059)Works with any cover
Pins groceries and gear against the bulkhead or tailgate so nothing slides around under a closed cover. It sits below rail height, so the cover closes over it. 40–70 in span; measure between your bed walls at the height you'll use it.
- Cargo managementRhino USA ratchet straps, 1 in × 15 ft (4-pack)Works with any cover
Tie-downs for loads strapped to a bed rack, or tall cargo you haul with a roll-up or folding cover open.
- Cargo managementMigaven heavy-duty truck bed cargo net, 4 × 6 ftWorks with any cover
The fallback when a load sticks up past the rails and the cover has to stay open: a stretch net over the bed keeps loose items in.
- Cargo managementRough Country slide-out truck bed cargo tray (10209)Works with any cover
Brings small items to the tailgate so you don't have to crawl under a cover to reach the front of the bed. Rough Country says the 4 in tray fits under any bed cover. Listing fitment: Trucks with a 5'7" or longer bed (tray is 62.3 × 23.6 × 4 in). Per the listing, fits beds 5'7" or longer; 5 ft midsize beds are too short.
- Cargo managementDECKED drawer system (XR7)Works with any cover
Two bed-length lockable drawers under a flat deck rated for 2,000 lb of cargo per the listing. Under a locking cover, it turns the bed into secure tool storage. Listing fitment: 2019–current Ram 1500 (DT) 6'4" bed, not RamBox. A drawer system raises the bed floor, which cuts the height left under a cover. DECKED sells a separate model for each truck and bed length.
- Bed matHusky Liners custom-fit rubberized bed mat (16008)Works with any cover
A rubberized mat with air-dry nibs underneath, so water that gets past a soft cover's seals can drain instead of sitting on the paint. Listing fitment: 2015–2026 Ford F-150 and 2022–2026 F-150 Lightning, 5'7" bed. Per the listing, it will not fit over a drop-in bed liner.
- Bed matRough Country heavy-duty rubber bed mat (RCM671)Works with any cover
A cheaper rubber mat that protects the floor and keeps cargo from sliding into the tailgate. Listing fitment: 2015–2027 Ford F-150, Lightning and Raptor, 5'7" (67 in) bed.
- Bed linerBedRug Classic bed liner (BRQ15SCK), charcoal greyWorks with any cover
A full-coverage foam-backed carpet-style liner for the floor, walls and tailgate: kneeling-friendly, and it stops cargo sliding around under a cover. Listing fitment: 2015–2024 Ford F-150 5'7" (5.5 ft) bed. Per the listing, the BRZSPRAYON install kit is required over a spray-in liner. If you run a clamp-on cover, make sure nothing sits on top of the bed rail where the clamps grip.
- Bed linerHerculiner HCL1B8 roll-on bed liner kit, black, 1 galWorks with any cover
The cheap DIY route to a textured, sealed bed floor. A coated bed sits under any cover type without changing how clamps or rails fit. One-gallon kit; check the coverage on the listing against your bed size before you buy.
Compatibility checked November 2026. More in our truck bed accessories guide.
Featured in our guides
- The 8 Best Tonneau Covers of 2026: Ranked by Type, Truck and Budget
- The Best Tonneau Covers for the Ford F-150 (2021–2026): 7 Picks by Bed and Budget
- The Best Tonneau Covers for the Ram 1500 (2019–2026): 7 Picks, Plus RamBox and Split-Tailgate Fit
- The Best Hard Tri-Fold Tonneau Covers of 2026: 6 Hard Folding Covers Compared
