BAKFlip MX4 for GMC Sierra | Hard Folding Tonneau Cover
We engineered the BAKFlip MX4 specifically for GMC Sierra owners who demand serious bed protection without compromising truck aesthetics. This hard folding tonneau cover features our signature 4-panel aluminum construction that sits flush with your truck bed rails for a low-profile look.
The MX4 operates with simple one-hand release latches and folds completely open against the cab for full bed access when you need it. Our dual-action tailgate seal keeps moisture and debris out while maintaining the ability to close your tailgate with the cover in any position. With a 10-year warranty backing every install, you're investing in tonneau cover performance that lasts as long as you own your Sierra.
MX4 construction & performance highlights
Aluminum Panel Construction & Finish
We build every BAKFlip MX4 panel from heavy-gauge aluminum that delivers impact resistance without adding unnecessary weight to your GMC Sierra. The powder-coated matte black finish integrates seamlessly with factory bed rail caps and resists scratching from cargo loads.
Each of the four panels connects through our reinforced FRP (Fiberglass Reinforced Polymer) hinge system that flexes through thousands of open-close cycles without cracking. This hinge design also allows you to position panels at 90-degree intervals, so you can cover just the front portion of your bed while leaving the rear open for taller cargo. The entire assembly maintains a tight seal against your Sierra’s bed rails through pre-installed weather stripping that runs the full perimeter.
GMC Sierra Fitment & Bed Compatibility
Model Year Coverage
The BAKFlip MX4 fits 2007-2025 GMC Sierra 1500, 2500HD, and 3500HD models in standard 5’8″, 6’6″, and 8′ bed lengths. We manufacture model-specific versions that account for changes in bed rail design across Sierra generations, so you get precise panel alignment on your truck.
Installation Requirements
Our integrated clamp system mounts directly to your factory bed rails in under 10 minutes with the included hex key. The MX4 works with or without a bed liner installed—if you’re running a spray-in liner, the cover sits on top of the bed rails as designed. For drop-in liners, we include spacer shims to maintain proper panel height. The cover is compatible with most fifth wheel and gooseneck hitch systems when panels are folded forward against the cab.
Operating the 4-Panel Folding System
We designed the MX4’s release mechanism for one-hand operation from either side of your Sierra. Squeeze the handle near each panel corner, lift, and the automatic struts assist panel movement through the folding sequence. You can stop at any panel to create partial bed access, or fold all four panels completely against the cab for full open-bed functionality.
The cover locks automatically when you close the panels—no separate latching step required. Our dual-action tailgate seal compresses against the rear panel whether your tailgate is open or closed, maintaining weather protection during transport. When you need to remove the entire cover for oversized cargo, the MX4 separates from the clamp system in seconds and stores upright against a garage wall without disassembly.
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Common Questions About the BAKFlip MX4 for GMC Sierra
Most Sierra owners complete MX4 installation in under 10 minutes without any drilling or permanent modifications. The integrated clamp system mounts directly to your factory bed rails using the included hex key.
You'll position the side rails on your bed, tighten the clamps to secure them, then set the pre-assembled 4-panel cover onto the rails. The entire process requires only the hex tool we provide—no additional equipment needed.
Yes, the MX4 features our dual-action tailgate seal that maintains weather protection whether your Sierra's tailgate is open or closed. You can drop the tailgate with the cover panels in any position without damaging the seal or reducing bed protection.
This design allows you to transport longer cargo with the tailgate down while keeping the front portion of your bed covered and secure.
The BAKFlip MX4 installs directly over spray-in liners without any compatibility issues. Our clamp system mounts to the top of your Sierra's bed rails, so the liner underneath doesn't interfere with cover operation or sealing.
For drop-in style bed liners, we include spacer shims in your MX4 package to maintain proper panel height and ensure the cover sits flush with your truck's profile.
We manufacture the BAKFlip MX4 for all three GMC Sierra bed lengths: 5'8" short bed, 6'6" standard bed, and 8' long bed. Each version is engineered specifically for that bed size to ensure panels align precisely with your truck's dimensions.
The MX4 fits 2007-2025 Sierra 1500, 2500HD, and 3500HD models. When ordering, confirm your truck's model year and bed length to receive the correct cover configuration.
The closed MX4 panels support up to 300 lbs when weight is distributed evenly across all four sections. This capacity handles snow accumulation, allows you to stand on the cover for bed access, or supports light equipment during transport.
The aluminum panel construction and reinforced hinge system prevent sagging under this load. Avoid concentrating weight on a single panel or hinge point to maintain the structural integrity of your cover.
Yes, the MX4 works with most fifth wheel and gooseneck hitch systems installed in GMC Sierra beds. When you fold all four panels forward against the cab, you create full clearance for hitch operation and trailer coupling.
For permanent hitch installations, measure your specific setup to confirm the folded panels don't interfere with your hitch head. Our customer service team can recommend compatible hitch adapters for your Sierra configuration if needed.
We back every BAKFlip MX4 with a 10-year warranty covering materials and workmanship defects. This warranty protects the aluminum panels, FRP hinge system, latching mechanism, clamp assembly, and powder-coat finish for a full decade from your purchase date.
The warranty transfers to subsequent owners if you sell your Sierra, which helps maintain your truck's resale value. Submit warranty claims through your BAKFlip account portal with photos and proof of purchase for expedited processing.